Adding upstream version 2.10.34.upstream/2.10.34upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2520 insertions, 0 deletions

diff --git a/app/tools/gimpgradienttool-editor.c b/app/tools/gimpgradienttool-editor.c
new file mode 100644
index 0000000..093c00b
--- /dev/null
+++ b/app/tools/gimpgradienttool-editor.c
@@ -0,0 +1,2520 @@
+/* GIMP - The GNU Image Manipulation Program
+ * Copyright (C) 1995 Spencer Kimball and Peter Mattis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <gegl.h>
+#include <gtk/gtk.h>
+#include <gdk/gdkkeysyms.h>
+
+#include "libgimpbase/gimpbase.h"
+#include "libgimpmath/gimpmath.h"
+#include "libgimpwidgets/gimpwidgets.h"
+
+#include "tools-types.h"
+
+#include "operations/gimp-operation-config.h"
+
+#include "core/gimpdata.h"
+#include "core/gimpgradient.h"
+#include "core/gimp-gradients.h"
+#include "core/gimpimage.h"
+
+#include "widgets/gimpcolorpanel.h"
+#include "widgets/gimpeditor.h"
+#include "widgets/gimpwidgets-utils.h"
+
+#include "display/gimpdisplay.h"
+#include "display/gimpdisplayshell.h"
+#include "display/gimptoolgui.h"
+#include "display/gimptoolline.h"
+
+#include "gimpgradientoptions.h"
+#include "gimpgradienttool.h"
+#include "gimpgradienttool-editor.h"
+
+#include "gimp-intl.h"
+
+
+#define EPSILON 2e-10
+
+
+typedef enum
+{
+  DIRECTION_NONE,
+  DIRECTION_LEFT,
+  DIRECTION_RIGHT
+} Direction;
+
+
+typedef struct
+{
+  /* line endpoints at the beginning of the operation */
+  gdouble       start_x;
+  gdouble       start_y;
+  gdouble       end_x;
+  gdouble       end_y;
+
+  /* copy of the gradient at the beginning of the operation, owned by the gradient
+   * info, or NULL, if the gradient isn't affected
+   */
+  GimpGradient *gradient;
+
+  /* handle added by the operation, or HANDLE_NONE */
+  gint          added_handle;
+  /* handle removed by the operation, or HANDLE_NONE */
+  gint          removed_handle;
+  /* selected handle at the end of the operation, or HANDLE_NONE */
+  gint          selected_handle;
+} GradientInfo;
+
+
+/*  local function prototypes  */
+
+static gboolean              gimp_gradient_tool_editor_line_can_add_slider           (GimpToolLine          *line,
+                                                                                      gdouble                value,
+                                                                                      GimpGradientTool      *gradient_tool);
+static gint                  gimp_gradient_tool_editor_line_add_slider               (GimpToolLine          *line,
+                                                                                      gdouble                value,
+                                                                                      GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_line_prepare_to_remove_slider (GimpToolLine          *line,
+                                                                                      gint                   slider,
+                                                                                      gboolean               remove,
+                                                                                      GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_line_remove_slider            (GimpToolLine          *line,
+                                                                                      gint                   slider,
+                                                                                      GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_line_selection_changed        (GimpToolLine          *line,
+                                                                                      GimpGradientTool      *gradient_tool);
+static gboolean              gimp_gradient_tool_editor_line_handle_clicked           (GimpToolLine          *line,
+                                                                                      gint                   handle,
+                                                                                      GdkModifierType        state,
+                                                                                      GimpButtonPressType    press_type,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_gui_response                  (GimpToolGui           *gui,
+                                                                                      gint                   response_id,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_color_entry_color_clicked     (GimpColorButton       *button,
+                                                                                      GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_color_entry_color_changed     (GimpColorButton       *button,
+                                                                                      GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_color_entry_color_response    (GimpColorButton       *button,
+                                                                                      GimpColorDialogState   state,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_color_entry_type_changed      (GtkComboBox           *combo,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_endpoint_se_value_changed     (GimpSizeEntry         *se,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_stop_se_value_changed         (GimpSizeEntry        *se,
+                                                                                      GimpGradientTool     *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_stop_delete_clicked           (GtkWidget             *button,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_midpoint_se_value_changed     (GimpSizeEntry        *se,
+                                                                                      GimpGradientTool     *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_midpoint_type_changed         (GtkComboBox           *combo,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_midpoint_color_changed        (GtkComboBox           *combo,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_midpoint_new_stop_clicked     (GtkWidget             *button,
+                                                                                      GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_midpoint_center_clicked       (GtkWidget             *button,
+                                                                                      GimpGradientTool      *gradient_tool);
+
+static gboolean              gimp_gradient_tool_editor_flush_idle                    (GimpGradientTool      *gradient_tool);
+
+static gboolean              gimp_gradient_tool_editor_is_gradient_editable          (GimpGradientTool      *gradient_tool);
+
+static gboolean              gimp_gradient_tool_editor_handle_is_endpoint            (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   handle);
+static gboolean              gimp_gradient_tool_editor_handle_is_stop                (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   handle);
+static gboolean              gimp_gradient_tool_editor_handle_is_midpoint            (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   handle);
+static GimpGradientSegment * gimp_gradient_tool_editor_handle_get_segment            (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   handle);
+
+static void                  gimp_gradient_tool_editor_block_handlers                (GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_unblock_handlers              (GimpGradientTool      *gradient_tool);
+static gboolean              gimp_gradient_tool_editor_are_handlers_blocked          (GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_freeze_gradient               (GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_thaw_gradient                 (GimpGradientTool      *gradient_tool);
+
+static gint                  gimp_gradient_tool_editor_add_stop                      (GimpGradientTool      *gradient_tool,
+                                                                                      gdouble                value);
+static void                  gimp_gradient_tool_editor_delete_stop                   (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   slider);
+static gint                  gimp_gradient_tool_editor_midpoint_to_stop              (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   slider);
+
+static void                  gimp_gradient_tool_editor_update_sliders                (GimpGradientTool      *gradient_tool);
+
+static void                  gimp_gradient_tool_editor_purge_gradient_history        (GSList               **stack);
+static void                  gimp_gradient_tool_editor_purge_gradient                (GimpGradientTool      *gradient_tool);
+
+static GtkWidget           * gimp_gradient_tool_editor_color_entry_new               (GimpGradientTool      *gradient_tool,
+                                                                                      const gchar           *title,
+                                                                                      Direction              direction,
+                                                                                      GtkWidget             *chain_button,
+                                                                                      GtkWidget            **color_panel,
+                                                                                      GtkWidget            **type_combo);
+static void                  gimp_gradient_tool_editor_init_endpoint_gui             (GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_init_stop_gui                 (GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_init_midpoint_gui             (GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_update_endpoint_gui           (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   selection);
+static void                  gimp_gradient_tool_editor_update_stop_gui               (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   selection);
+static void                  gimp_gradient_tool_editor_update_midpoint_gui           (GimpGradientTool      *gradient_tool,
+                                                                                      gint                   selection);
+static void                  gimp_gradient_tool_editor_update_gui                    (GimpGradientTool      *gradient_tool);
+
+static GradientInfo        * gimp_gradient_tool_editor_gradient_info_new             (GimpGradientTool      *gradient_tool);
+static void                  gimp_gradient_tool_editor_gradient_info_free            (GradientInfo          *info);
+static void                  gimp_gradient_tool_editor_gradient_info_apply           (GimpGradientTool      *gradient_tool,
+                                                                                      const GradientInfo    *info,
+                                                                                      gboolean               set_selection);
+static gboolean              gimp_gradient_tool_editor_gradient_info_is_trivial      (GimpGradientTool      *gradient_tool,
+                                                                                      const GradientInfo    *info);
+
+
+/*  private functions  */
+
+
+static gboolean
+gimp_gradient_tool_editor_line_can_add_slider (GimpToolLine  *line,
+                                               gdouble        value,
+                                               GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions *options = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  gdouble              offset  = options->offset / 100.0;
+
+  return gimp_gradient_tool_editor_is_gradient_editable (gradient_tool) &&
+         value >= offset;
+}
+
+static gint
+gimp_gradient_tool_editor_line_add_slider (GimpToolLine     *line,
+                                           gdouble           value,
+                                           GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions *options       = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpPaintOptions    *paint_options = GIMP_PAINT_OPTIONS (options);
+  gdouble              offset        = options->offset / 100.0;
+
+  /* adjust slider value according to the offset */
+  value = (value - offset) / (1.0 - offset);
+
+  /* flip the slider value, if necessary */
+  if (paint_options->gradient_options->gradient_reverse)
+    value = 1.0 - value;
+
+  return gimp_gradient_tool_editor_add_stop (gradient_tool, value);
+}
+
+static void
+gimp_gradient_tool_editor_line_prepare_to_remove_slider (GimpToolLine     *line,
+                                                         gint              slider,
+                                                         gboolean          remove,
+                                                         GimpGradientTool *gradient_tool)
+{
+  if (remove)
+    {
+      GradientInfo *info;
+      GimpGradient *tentative_gradient;
+
+      /* show a tentative gradient, demonstrating the result of actually
+       * removing the slider
+       */
+
+      info = gradient_tool->undo_stack->data;
+
+      if (info->added_handle == slider)
+        {
+          /* see comment in gimp_gradient_tool_editor_delete_stop() */
+
+          gimp_assert (info->gradient != NULL);
+
+          tentative_gradient = g_object_ref (info->gradient);
+        }
+      else
+        {
+          GimpGradientSegment *seg;
+          gint                 i;
+
+          tentative_gradient =
+            GIMP_GRADIENT (gimp_data_duplicate (GIMP_DATA (gradient_tool->gradient)));
+
+          seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, slider);
+
+          i = gimp_gradient_segment_range_get_n_segments (gradient_tool->gradient,
+                                                          gradient_tool->gradient->segments,
+                                                          seg) - 1;
+
+          seg = gimp_gradient_segment_get_nth (tentative_gradient->segments, i);
+
+          gimp_gradient_segment_range_merge (tentative_gradient,
+                                             seg, seg->next, NULL, NULL);
+        }
+
+      gimp_gradient_tool_set_tentative_gradient (gradient_tool, tentative_gradient);
+
+      g_object_unref (tentative_gradient);
+    }
+  else
+    {
+      gimp_gradient_tool_set_tentative_gradient (gradient_tool, NULL);
+    }
+}
+
+static void
+gimp_gradient_tool_editor_line_remove_slider (GimpToolLine     *line,
+                                              gint              slider,
+                                              GimpGradientTool *gradient_tool)
+{
+  gimp_gradient_tool_editor_delete_stop (gradient_tool, slider);
+  gimp_gradient_tool_set_tentative_gradient (gradient_tool, NULL);
+}
+
+static void
+gimp_gradient_tool_editor_line_selection_changed (GimpToolLine     *line,
+                                                  GimpGradientTool *gradient_tool)
+{
+  gint selection;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  if (gradient_tool->gui)
+    {
+      /* hide all color dialogs */
+      gimp_color_panel_dialog_response (
+        GIMP_COLOR_PANEL (gradient_tool->endpoint_color_panel),
+        GIMP_COLOR_DIALOG_OK);
+      gimp_color_panel_dialog_response (
+        GIMP_COLOR_PANEL (gradient_tool->stop_left_color_panel),
+        GIMP_COLOR_DIALOG_OK);
+      gimp_color_panel_dialog_response (
+        GIMP_COLOR_PANEL (gradient_tool->stop_right_color_panel),
+        GIMP_COLOR_DIALOG_OK);
+
+      /* reset the stop colors chain button */
+      if (gimp_gradient_tool_editor_handle_is_stop (gradient_tool, selection))
+        {
+          const GimpGradientSegment *seg;
+          gboolean                   homogeneous;
+
+          seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool,
+                                                              selection);
+
+          homogeneous = seg->right_color.r    == seg->next->left_color.r &&
+                        seg->right_color.g    == seg->next->left_color.g &&
+                        seg->right_color.b    == seg->next->left_color.b &&
+                        seg->right_color.a    == seg->next->left_color.a &&
+                        seg->right_color_type == seg->next->left_color_type;
+
+          gimp_chain_button_set_active (
+            GIMP_CHAIN_BUTTON (gradient_tool->stop_chain_button), homogeneous);
+        }
+    }
+
+  gimp_gradient_tool_editor_update_gui (gradient_tool);
+}
+
+static gboolean
+gimp_gradient_tool_editor_line_handle_clicked (GimpToolLine        *line,
+                                               gint                 handle,
+                                               GdkModifierType      state,
+                                               GimpButtonPressType  press_type,
+                                               GimpGradientTool    *gradient_tool)
+{
+  if (gimp_gradient_tool_editor_handle_is_midpoint (gradient_tool, handle))
+    {
+      if (press_type == GIMP_BUTTON_PRESS_DOUBLE &&
+          gimp_gradient_tool_editor_is_gradient_editable (gradient_tool))
+        {
+          gint stop;
+
+          stop = gimp_gradient_tool_editor_midpoint_to_stop (gradient_tool, handle);
+
+          gimp_tool_line_set_selection (line, stop);
+
+          /* return FALSE, so that the new slider can be dragged immediately */
+          return FALSE;
+        }
+    }
+
+  return FALSE;
+}
+
+
+static void
+gimp_gradient_tool_editor_gui_response (GimpToolGui      *gui,
+                                        gint              response_id,
+                                        GimpGradientTool *gradient_tool)
+{
+  switch (response_id)
+    {
+    default:
+      gimp_tool_line_set_selection (GIMP_TOOL_LINE (gradient_tool->widget),
+                                    GIMP_TOOL_LINE_HANDLE_NONE);
+      break;
+    }
+}
+
+static void
+gimp_gradient_tool_editor_color_entry_color_clicked (GimpColorButton  *button,
+                                                     GimpGradientTool *gradient_tool)
+{
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+}
+
+static void
+gimp_gradient_tool_editor_color_entry_color_changed (GimpColorButton  *button,
+                                                     GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions *options       = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpPaintOptions    *paint_options = GIMP_PAINT_OPTIONS (options);
+  gint                 selection;
+  GimpRGB              color;
+  Direction            direction;
+  GtkWidget           *chain_button;
+  GimpGradientSegment *seg;
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  gimp_color_button_get_color (button, &color);
+
+  direction =
+    GPOINTER_TO_INT (g_object_get_data (G_OBJECT (button),
+                                        "gimp-gradient-tool-editor-direction"));
+  chain_button = g_object_get_data (G_OBJECT (button),
+                                    "gimp-gradient-tool-editor-chain-button");
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  /* swap the endpoint handles, if necessary */
+  if (paint_options->gradient_options->gradient_reverse)
+    {
+      switch (selection)
+        {
+        case GIMP_TOOL_LINE_HANDLE_START:
+          selection = GIMP_TOOL_LINE_HANDLE_END;
+          break;
+
+        case GIMP_TOOL_LINE_HANDLE_END:
+          selection = GIMP_TOOL_LINE_HANDLE_START;
+          break;
+        }
+    }
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  switch (selection)
+    {
+    case GIMP_TOOL_LINE_HANDLE_START:
+      seg->left_color      = color;
+      seg->left_color_type = GIMP_GRADIENT_COLOR_FIXED;
+      break;
+
+    case GIMP_TOOL_LINE_HANDLE_END:
+      seg->right_color      = color;
+      seg->right_color_type = GIMP_GRADIENT_COLOR_FIXED;
+      break;
+
+    default:
+      if (direction == DIRECTION_LEFT ||
+          (chain_button               &&
+           gimp_chain_button_get_active (GIMP_CHAIN_BUTTON (chain_button))))
+        {
+          seg->right_color      = color;
+          seg->right_color_type = GIMP_GRADIENT_COLOR_FIXED;
+        }
+
+      if (direction == DIRECTION_RIGHT ||
+          (chain_button                &&
+           gimp_chain_button_get_active (GIMP_CHAIN_BUTTON (chain_button))))
+        {
+          seg->next->left_color      = color;
+          seg->next->left_color_type = GIMP_GRADIENT_COLOR_FIXED;
+        }
+    }
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static void
+gimp_gradient_tool_editor_color_entry_color_response (GimpColorButton      *button,
+                                                      GimpColorDialogState  state,
+                                                      GimpGradientTool     *gradient_tool)
+{
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static void
+gimp_gradient_tool_editor_color_entry_type_changed (GtkComboBox      *combo,
+                                                    GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions *options       = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpPaintOptions    *paint_options = GIMP_PAINT_OPTIONS (options);
+  gint                 selection;
+  gint                 color_type;
+  Direction            direction;
+  GtkWidget           *chain_button;
+  GimpGradientSegment *seg;
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  if (! gimp_int_combo_box_get_active (GIMP_INT_COMBO_BOX (combo), &color_type))
+    return;
+
+  direction =
+    GPOINTER_TO_INT (g_object_get_data (G_OBJECT (combo),
+                                        "gimp-gradient-tool-editor-direction"));
+  chain_button = g_object_get_data (G_OBJECT (combo),
+                                    "gimp-gradient-tool-editor-chain-button");
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  /* swap the endpoint handles, if necessary */
+  if (paint_options->gradient_options->gradient_reverse)
+    {
+      switch (selection)
+        {
+        case GIMP_TOOL_LINE_HANDLE_START:
+          selection = GIMP_TOOL_LINE_HANDLE_END;
+          break;
+
+        case GIMP_TOOL_LINE_HANDLE_END:
+          selection = GIMP_TOOL_LINE_HANDLE_START;
+          break;
+        }
+    }
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  switch (selection)
+    {
+    case GIMP_TOOL_LINE_HANDLE_START:
+      seg->left_color_type = color_type;
+      break;
+
+    case GIMP_TOOL_LINE_HANDLE_END:
+      seg->right_color_type = color_type;
+      break;
+
+    default:
+      if (direction == DIRECTION_LEFT ||
+          (chain_button               &&
+           gimp_chain_button_get_active (GIMP_CHAIN_BUTTON (chain_button))))
+        {
+          seg->right_color_type = color_type;
+        }
+
+      if (direction == DIRECTION_RIGHT ||
+          (chain_button                &&
+           gimp_chain_button_get_active (GIMP_CHAIN_BUTTON (chain_button))))
+        {
+          seg->next->left_color_type = color_type;
+        }
+    }
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static void
+gimp_gradient_tool_editor_endpoint_se_value_changed (GimpSizeEntry    *se,
+                                                     GimpGradientTool *gradient_tool)
+{
+  gint    selection;
+  gdouble x;
+  gdouble y;
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  if (selection == GIMP_TOOL_LINE_HANDLE_NONE)
+    return;
+
+  x = gimp_size_entry_get_refval (se, 0);
+  y = gimp_size_entry_get_refval (se, 1);
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_block_handlers (gradient_tool);
+
+  switch (selection)
+    {
+    case GIMP_TOOL_LINE_HANDLE_START:
+      g_object_set (gradient_tool->widget,
+                    "x1", x,
+                    "y1", y,
+                    NULL);
+      break;
+
+    case GIMP_TOOL_LINE_HANDLE_END:
+      g_object_set (gradient_tool->widget,
+                    "x2", x,
+                    "y2", y,
+                    NULL);
+      break;
+
+    default:
+      gimp_assert_not_reached ();
+    }
+
+  gimp_gradient_tool_editor_unblock_handlers (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static void
+gimp_gradient_tool_editor_stop_se_value_changed (GimpSizeEntry    *se,
+                                                 GimpGradientTool *gradient_tool)
+{
+  gint                 selection;
+  gdouble              value;
+  GimpGradientSegment *seg;
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  if (selection == GIMP_TOOL_LINE_HANDLE_NONE)
+    return;
+
+  value = gimp_size_entry_get_refval (se, 0) / 100.0;
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  gimp_gradient_segment_range_compress (gradient_tool->gradient,
+                                        seg, seg,
+                                        seg->left, value);
+  gimp_gradient_segment_range_compress (gradient_tool->gradient,
+                                        seg->next, seg->next,
+                                        value, seg->next->right);
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static void
+gimp_gradient_tool_editor_stop_delete_clicked (GtkWidget        *button,
+                                               GimpGradientTool *gradient_tool)
+{
+  gint selection;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  gimp_gradient_tool_editor_delete_stop (gradient_tool, selection);
+}
+
+static void
+gimp_gradient_tool_editor_midpoint_se_value_changed (GimpSizeEntry    *se,
+                                                     GimpGradientTool *gradient_tool)
+{
+  gint                 selection;
+  gdouble              value;
+  GimpGradientSegment *seg;
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  if (selection == GIMP_TOOL_LINE_HANDLE_NONE)
+    return;
+
+  value = gimp_size_entry_get_refval (se, 0) / 100.0;
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  seg->middle = value;
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static void
+gimp_gradient_tool_editor_midpoint_type_changed (GtkComboBox      *combo,
+                                                 GimpGradientTool *gradient_tool)
+{
+  gint                 selection;
+  gint                 type;
+  GimpGradientSegment *seg;
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  if (! gimp_int_combo_box_get_active (GIMP_INT_COMBO_BOX (combo), &type))
+    return;
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  seg->type = type;
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static void
+gimp_gradient_tool_editor_midpoint_color_changed (GtkComboBox      *combo,
+                                                  GimpGradientTool *gradient_tool)
+{
+  gint                 selection;
+  gint                 color;
+  GimpGradientSegment *seg;
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  if (! gimp_int_combo_box_get_active (GIMP_INT_COMBO_BOX (combo), &color))
+    return;
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  seg->color = color;
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static void
+gimp_gradient_tool_editor_midpoint_new_stop_clicked (GtkWidget        *button,
+                                                     GimpGradientTool *gradient_tool)
+{
+  gint selection;
+  gint stop;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  stop = gimp_gradient_tool_editor_midpoint_to_stop (gradient_tool, selection);
+
+  gimp_tool_line_set_selection (GIMP_TOOL_LINE (gradient_tool->widget), stop);
+}
+
+static void
+gimp_gradient_tool_editor_midpoint_center_clicked (GtkWidget        *button,
+                                                   GimpGradientTool *gradient_tool)
+{
+  gint                 selection;
+  GimpGradientSegment *seg;
+
+  selection =
+    gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  gimp_gradient_segment_range_recenter_handles (gradient_tool->gradient, seg, seg);
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static gboolean
+gimp_gradient_tool_editor_flush_idle (GimpGradientTool *gradient_tool)
+{
+  GimpDisplay *display = GIMP_TOOL (gradient_tool)->display;
+
+  gimp_image_flush (gimp_display_get_image (display));
+
+  gradient_tool->flush_idle_id = 0;
+
+  return G_SOURCE_REMOVE;
+}
+
+static gboolean
+gimp_gradient_tool_editor_is_gradient_editable (GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions *options = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+
+  return ! options->modify_active ||
+         gimp_data_is_writable (GIMP_DATA (gradient_tool->gradient));
+}
+
+static gboolean
+gimp_gradient_tool_editor_handle_is_endpoint (GimpGradientTool *gradient_tool,
+                                              gint              handle)
+{
+  return handle == GIMP_TOOL_LINE_HANDLE_START ||
+         handle == GIMP_TOOL_LINE_HANDLE_END;
+}
+
+static gboolean
+gimp_gradient_tool_editor_handle_is_stop (GimpGradientTool *gradient_tool,
+                                          gint              handle)
+{
+  gint n_sliders;
+
+  gimp_tool_line_get_sliders (GIMP_TOOL_LINE (gradient_tool->widget), &n_sliders);
+
+  return handle >= 0 && handle < n_sliders / 2;
+}
+
+static gboolean
+gimp_gradient_tool_editor_handle_is_midpoint (GimpGradientTool *gradient_tool,
+                                              gint              handle)
+{
+  gint n_sliders;
+
+  gimp_tool_line_get_sliders (GIMP_TOOL_LINE (gradient_tool->widget), &n_sliders);
+
+  return handle >= n_sliders / 2;
+}
+
+static GimpGradientSegment *
+gimp_gradient_tool_editor_handle_get_segment (GimpGradientTool *gradient_tool,
+                                              gint              handle)
+{
+  switch (handle)
+    {
+    case GIMP_TOOL_LINE_HANDLE_START:
+      return gradient_tool->gradient->segments;
+
+    case GIMP_TOOL_LINE_HANDLE_END:
+      return gimp_gradient_segment_get_last (gradient_tool->gradient->segments);
+
+    default:
+      {
+        const GimpControllerSlider *sliders;
+        gint                        n_sliders;
+        gint                        seg_i;
+
+        sliders = gimp_tool_line_get_sliders (GIMP_TOOL_LINE (gradient_tool->widget),
+                                              &n_sliders);
+
+        gimp_assert (handle >= 0 && handle < n_sliders);
+
+        seg_i = GPOINTER_TO_INT (sliders[handle].data);
+
+        return gimp_gradient_segment_get_nth (gradient_tool->gradient->segments,
+                                              seg_i);
+      }
+    }
+}
+
+static void
+gimp_gradient_tool_editor_block_handlers (GimpGradientTool *gradient_tool)
+{
+  gradient_tool->block_handlers_count++;
+}
+
+static void
+gimp_gradient_tool_editor_unblock_handlers (GimpGradientTool *gradient_tool)
+{
+  gimp_assert (gradient_tool->block_handlers_count > 0);
+
+  gradient_tool->block_handlers_count--;
+}
+
+static gboolean
+gimp_gradient_tool_editor_are_handlers_blocked (GimpGradientTool *gradient_tool)
+{
+  return gradient_tool->block_handlers_count > 0;
+}
+
+static void
+gimp_gradient_tool_editor_freeze_gradient (GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions *options = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpGradient        *custom;
+  GradientInfo           *info;
+
+  gimp_gradient_tool_editor_block_handlers (gradient_tool);
+
+  custom = gimp_gradients_get_custom (GIMP_CONTEXT (options)->gimp);
+
+  if (gradient_tool->gradient == custom || options->modify_active)
+    {
+      gimp_assert (gimp_gradient_tool_editor_is_gradient_editable (gradient_tool));
+
+      gimp_data_freeze (GIMP_DATA (gradient_tool->gradient));
+    }
+  else
+    {
+      /* copy the active gradient to the custom gradient, and make the custom
+       * gradient active.
+       */
+      gimp_data_freeze (GIMP_DATA (custom));
+
+      gimp_data_copy (GIMP_DATA (custom), GIMP_DATA (gradient_tool->gradient));
+
+      gimp_context_set_gradient (GIMP_CONTEXT (options), custom);
+
+      gimp_assert (gradient_tool->gradient == custom);
+      gimp_assert (gimp_gradient_tool_editor_is_gradient_editable (gradient_tool));
+    }
+
+  if (gradient_tool->edit_count > 0)
+    {
+      info = gradient_tool->undo_stack->data;
+
+      if (! info->gradient)
+        {
+          info->gradient =
+            GIMP_GRADIENT (gimp_data_duplicate (GIMP_DATA (gradient_tool->gradient)));
+        }
+    }
+}
+
+static void
+gimp_gradient_tool_editor_thaw_gradient (GimpGradientTool *gradient_tool)
+{
+  gimp_data_thaw (GIMP_DATA (gradient_tool->gradient));
+
+  gimp_gradient_tool_editor_update_sliders (gradient_tool);
+  gimp_gradient_tool_editor_update_gui (gradient_tool);
+
+  gimp_gradient_tool_editor_unblock_handlers (gradient_tool);
+}
+
+static gint
+gimp_gradient_tool_editor_add_stop (GimpGradientTool *gradient_tool,
+                                    gdouble           value)
+{
+  GimpGradientOptions *options       = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpPaintOptions    *paint_options = GIMP_PAINT_OPTIONS (options);
+  GimpGradientSegment *seg;
+  gint                 stop;
+  GradientInfo           *info;
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  gimp_gradient_split_at (gradient_tool->gradient,
+                          GIMP_CONTEXT (options), NULL, value,
+                          paint_options->gradient_options->gradient_blend_color_space,
+                          &seg, NULL);
+
+  stop =
+    gimp_gradient_segment_range_get_n_segments (gradient_tool->gradient,
+                                                gradient_tool->gradient->segments,
+                                                seg) - 1;
+
+  info               = gradient_tool->undo_stack->data;
+  info->added_handle = stop;
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+
+  return stop;
+}
+
+static void
+gimp_gradient_tool_editor_delete_stop (GimpGradientTool *gradient_tool,
+                                       gint              slider)
+{
+  GradientInfo *info;
+
+  gimp_assert (gimp_gradient_tool_editor_handle_is_stop (gradient_tool, slider));
+
+  gimp_gradient_tool_editor_start_edit (gradient_tool);
+  gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+  info = gradient_tool->undo_stack->data;
+
+  if (info->added_handle == slider)
+    {
+      /* when removing a stop that was added as part of the current action,
+       * restore the original gradient at the beginning of the action, rather
+       * than deleting the stop from the current gradient, so that the affected
+       * midpoint returns to its state at the beginning of the action, instead
+       * of being reset.
+       *
+       * note that this assumes that the gradient hasn't changed in any other
+       * way during the action, which is ugly, but currently always true.
+       */
+
+      gimp_assert (info->gradient != NULL);
+
+      gimp_data_copy (GIMP_DATA (gradient_tool->gradient),
+                      GIMP_DATA (info->gradient));
+
+      g_clear_object (&info->gradient);
+
+      info->added_handle = GIMP_TOOL_LINE_HANDLE_NONE;
+    }
+  else
+    {
+      GimpGradientSegment *seg;
+
+      seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, slider);
+
+      gimp_gradient_segment_range_merge (gradient_tool->gradient,
+                                         seg, seg->next, NULL, NULL);
+
+      info->removed_handle = slider;
+    }
+
+  gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+  gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+}
+
+static gint
+gimp_gradient_tool_editor_midpoint_to_stop (GimpGradientTool *gradient_tool,
+                                            gint              slider)
+{
+  const GimpControllerSlider *sliders;
+
+  gimp_assert (gimp_gradient_tool_editor_handle_is_midpoint (gradient_tool, slider));
+
+  sliders = gimp_tool_line_get_sliders (GIMP_TOOL_LINE (gradient_tool->widget),
+                                        NULL);
+
+  if (sliders[slider].value > sliders[slider].min + EPSILON &&
+      sliders[slider].value < sliders[slider].max - EPSILON)
+    {
+      const GimpGradientSegment *seg;
+      gint                       stop;
+      GradientInfo                 *info;
+
+      seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, slider);
+
+      stop = gimp_gradient_tool_editor_add_stop (gradient_tool, seg->middle);
+
+      info                 = gradient_tool->undo_stack->data;
+      info->removed_handle = slider;
+
+      slider = stop;
+    }
+
+  return slider;
+}
+
+static void
+gimp_gradient_tool_editor_update_sliders (GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions  *options       = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpPaintOptions     *paint_options = GIMP_PAINT_OPTIONS (options);
+  gdouble               offset        = options->offset / 100.0;
+  gboolean              editable;
+  GimpControllerSlider *sliders;
+  gint                  n_sliders;
+  gint                  n_segments;
+  GimpGradientSegment  *seg;
+  GimpControllerSlider *slider;
+  gint                  i;
+
+  if (! gradient_tool->widget || options->instant)
+    return;
+
+  editable = gimp_gradient_tool_editor_is_gradient_editable (gradient_tool);
+
+  n_segments = gimp_gradient_segment_range_get_n_segments (
+    gradient_tool->gradient, gradient_tool->gradient->segments, NULL);
+
+  n_sliders = (n_segments - 1) + /* gradient stops, between each adjacent
+                                  * pair of segments */
+              (n_segments);      /* midpoints, inside each segment */
+
+  sliders = g_new (GimpControllerSlider, n_sliders);
+
+  slider = sliders;
+
+  /* initialize the gradient-stop sliders */
+  for (seg = gradient_tool->gradient->segments, i = 0;
+       seg->next;
+       seg = seg->next, i++)
+    {
+      *slider = GIMP_CONTROLLER_SLIDER_DEFAULT;
+
+      slider->value     = seg->right;
+      slider->min       = seg->left;
+      slider->max       = seg->next->right;
+
+      slider->movable   = editable;
+      slider->removable = editable;
+
+      slider->data      = GINT_TO_POINTER (i);
+
+      slider++;
+    }
+
+  /* initialize the midpoint sliders */
+  for (seg = gradient_tool->gradient->segments, i = 0;
+       seg;
+       seg = seg->next, i++)
+    {
+      *slider = GIMP_CONTROLLER_SLIDER_DEFAULT;
+
+      slider->value    = seg->middle;
+      slider->min      = seg->left;
+      slider->max      = seg->right;
+
+      /* hide midpoints of zero-length segments, since they'd otherwise
+       * prevent the segment's endpoints from being selected
+       */
+      slider->visible  = fabs (slider->max - slider->min) > EPSILON;
+      slider->movable  = editable;
+
+      slider->autohide = TRUE;
+      slider->type     = GIMP_HANDLE_FILLED_CIRCLE;
+      slider->size     = 0.6;
+
+      slider->data     = GINT_TO_POINTER (i);
+
+      slider++;
+    }
+
+  /* flip the slider limits and values, if necessary */
+  if (paint_options->gradient_options->gradient_reverse)
+    {
+      for (i = 0; i < n_sliders; i++)
+        {
+          gdouble temp;
+
+          sliders[i].value = 1.0 - sliders[i].value;
+          temp             = sliders[i].min;
+          sliders[i].min   = 1.0 - sliders[i].max;
+          sliders[i].max   = 1.0 - temp;
+        }
+    }
+
+  /* adjust the sliders according to the offset */
+  for (i = 0; i < n_sliders; i++)
+    {
+      sliders[i].value = (1.0 - offset) * sliders[i].value + offset;
+      sliders[i].min   = (1.0 - offset) * sliders[i].min   + offset;
+      sliders[i].max   = (1.0 - offset) * sliders[i].max   + offset;
+    }
+
+  /* avoid updating the gradient in gimp_gradient_tool_editor_line_changed() */
+  gimp_gradient_tool_editor_block_handlers (gradient_tool);
+
+  gimp_tool_line_set_sliders (GIMP_TOOL_LINE (gradient_tool->widget),
+                              sliders, n_sliders);
+
+  gimp_gradient_tool_editor_unblock_handlers (gradient_tool);
+
+  g_free (sliders);
+}
+
+static void
+gimp_gradient_tool_editor_purge_gradient_history (GSList **stack)
+{
+  GSList *link;
+
+  /* eliminate all history steps that modify the gradient */
+  while ((link = *stack))
+    {
+      GradientInfo *info = link->data;
+
+      if (info->gradient)
+        {
+          gimp_gradient_tool_editor_gradient_info_free (info);
+
+          *stack = g_slist_delete_link (*stack, link);
+        }
+      else
+        {
+          stack = &link->next;
+        }
+    }
+}
+
+static void
+gimp_gradient_tool_editor_purge_gradient (GimpGradientTool *gradient_tool)
+{
+  if (gradient_tool->widget)
+    {
+      gimp_gradient_tool_editor_update_sliders (gradient_tool);
+
+      gimp_tool_line_set_selection (GIMP_TOOL_LINE (gradient_tool->widget),
+                                    GIMP_TOOL_LINE_HANDLE_NONE);
+    }
+
+  gimp_gradient_tool_editor_purge_gradient_history (&gradient_tool->undo_stack);
+  gimp_gradient_tool_editor_purge_gradient_history (&gradient_tool->redo_stack);
+}
+
+static GtkWidget *
+gimp_gradient_tool_editor_color_entry_new (GimpGradientTool  *gradient_tool,
+                                           const gchar       *title,
+                                           Direction          direction,
+                                           GtkWidget         *chain_button,
+                                           GtkWidget        **color_panel,
+                                           GtkWidget        **type_combo)
+{
+  GimpContext *context = GIMP_CONTEXT (GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool));
+  GtkWidget   *hbox;
+  GtkWidget   *button;
+  GtkWidget   *combo;
+  GimpRGB      color   = {};
+
+  hbox = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 2);
+
+  /* the color panel */
+  *color_panel = button = gimp_color_panel_new (title, &color,
+                                                GIMP_COLOR_AREA_SMALL_CHECKS,
+                                                24, 24);
+  gimp_color_button_set_update (GIMP_COLOR_BUTTON (button), TRUE);
+  gimp_color_panel_set_context (GIMP_COLOR_PANEL (button), context);
+  gtk_box_pack_start (GTK_BOX (hbox), button, TRUE, TRUE, 0);
+  gtk_widget_show (button);
+
+  g_object_set_data (G_OBJECT (button),
+                     "gimp-gradient-tool-editor-direction",
+                     GINT_TO_POINTER (direction));
+  g_object_set_data (G_OBJECT (button),
+                     "gimp-gradient-tool-editor-chain-button",
+                     chain_button);
+
+  g_signal_connect (button, "clicked",
+                    G_CALLBACK (gimp_gradient_tool_editor_color_entry_color_clicked),
+                    gradient_tool);
+  g_signal_connect (button, "color-changed",
+                    G_CALLBACK (gimp_gradient_tool_editor_color_entry_color_changed),
+                    gradient_tool);
+  g_signal_connect (button, "response",
+                    G_CALLBACK (gimp_gradient_tool_editor_color_entry_color_response),
+                    gradient_tool);
+
+  /* the color type combo */
+  *type_combo = combo = gimp_enum_combo_box_new (GIMP_TYPE_GRADIENT_COLOR);
+  gtk_box_pack_start (GTK_BOX (hbox), combo, FALSE, TRUE, 0);
+  gtk_widget_show (combo);
+
+  g_object_set_data (G_OBJECT (combo),
+                     "gimp-gradient-tool-editor-direction",
+                     GINT_TO_POINTER (direction));
+  g_object_set_data (G_OBJECT (combo),
+                     "gimp-gradient-tool-editor-chain-button",
+                     chain_button);
+
+  g_signal_connect (combo, "changed",
+                    G_CALLBACK (gimp_gradient_tool_editor_color_entry_type_changed),
+                    gradient_tool);
+
+  return hbox;
+}
+
+static void
+gimp_gradient_tool_editor_init_endpoint_gui (GimpGradientTool *gradient_tool)
+{
+  GimpDisplay      *display = GIMP_TOOL (gradient_tool)->display;
+  GimpDisplayShell *shell   = gimp_display_get_shell (display);
+  GimpImage        *image   = gimp_display_get_image (display);
+  gdouble           xres;
+  gdouble           yres;
+  GtkWidget        *editor;
+  GtkWidget        *table;
+  GtkWidget        *label;
+  GtkWidget        *spinbutton;
+  GtkWidget        *se;
+  GtkWidget        *hbox;
+  gint              row     = 0;
+
+  gimp_image_get_resolution (image, &xres, &yres);
+
+  /* the endpoint editor */
+  gradient_tool->endpoint_editor =
+  editor                         = gimp_editor_new ();
+  gtk_box_pack_start (GTK_BOX (gimp_tool_gui_get_vbox (gradient_tool->gui)),
+                      editor, FALSE, TRUE, 0);
+
+  /* the main table */
+  table = gtk_table_new (1, 2, FALSE);
+  gtk_table_set_row_spacings (GTK_TABLE (table), 4);
+  gtk_table_set_col_spacings (GTK_TABLE (table), 4);
+  gtk_box_pack_start (GTK_BOX (editor), table, FALSE, TRUE, 0);
+  gtk_widget_show (table);
+
+  /* the position labels */
+  label = gtk_label_new (_("X:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row, row + 1,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  label = gtk_label_new (_("Y:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row + 1, row + 2,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  /* the position size entry */
+  spinbutton = gimp_spin_button_new_with_range (0.0, 0.0, 1.0);
+  gtk_spin_button_set_numeric (GTK_SPIN_BUTTON (spinbutton), TRUE);
+  gtk_entry_set_width_chars (GTK_ENTRY (spinbutton), 6);
+
+  gradient_tool->endpoint_se =
+  se                         = gimp_size_entry_new (1, GIMP_UNIT_PIXEL, "%a",
+                                                    TRUE, TRUE, FALSE, 6,
+                                                    GIMP_SIZE_ENTRY_UPDATE_SIZE);
+  gtk_table_set_row_spacings (GTK_TABLE (se), 4);
+  gtk_table_set_col_spacings (GTK_TABLE (se), 2);
+
+  gimp_size_entry_add_field (GIMP_SIZE_ENTRY (se),
+                             GTK_SPIN_BUTTON (spinbutton), NULL);
+  gtk_table_attach_defaults (GTK_TABLE (se), spinbutton, 1, 2, 0, 1);
+  gtk_widget_show (spinbutton);
+
+  gtk_table_attach (GTK_TABLE (table), se, 1, 2, row, row + 2,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (se);
+
+  gimp_size_entry_set_unit (GIMP_SIZE_ENTRY (se), shell->unit);
+
+  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (se), 0, xres, FALSE);
+  gimp_size_entry_set_resolution (GIMP_SIZE_ENTRY (se), 1, yres, FALSE);
+
+  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (se), 0,
+                                         -GIMP_MAX_IMAGE_SIZE,
+                                         GIMP_MAX_IMAGE_SIZE);
+  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (se), 1,
+                                         -GIMP_MAX_IMAGE_SIZE,
+                                         GIMP_MAX_IMAGE_SIZE);
+
+  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (se), 0,
+                            0, gimp_image_get_width (image));
+  gimp_size_entry_set_size (GIMP_SIZE_ENTRY (se), 1,
+                            0, gimp_image_get_height (image));
+
+  g_signal_connect (se, "value-changed",
+                    G_CALLBACK (gimp_gradient_tool_editor_endpoint_se_value_changed),
+                    gradient_tool);
+
+  row += 2;
+
+  /* the color label */
+  label = gtk_label_new (_("Color:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row, row + 1,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  /* the color entry */
+  hbox = gimp_gradient_tool_editor_color_entry_new (
+    gradient_tool, _("Change Endpoint Color"), DIRECTION_NONE, NULL,
+    &gradient_tool->endpoint_color_panel, &gradient_tool->endpoint_type_combo);
+  gtk_table_attach (GTK_TABLE (table), hbox, 1, 2, row, row + 1,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (hbox);
+
+  row++;
+}
+
+static void
+gimp_gradient_tool_editor_init_stop_gui (GimpGradientTool *gradient_tool)
+{
+  GtkWidget *editor;
+  GtkWidget *table;
+  GtkWidget *label;
+  GtkWidget *se;
+  GtkWidget *table2;
+  GtkWidget *button;
+  GtkWidget *hbox;
+  GtkWidget *separator;
+  gint       row = 0;
+
+  /* the stop editor */
+  gradient_tool->stop_editor =
+  editor                     = gimp_editor_new ();
+  gtk_box_pack_start (GTK_BOX (gimp_tool_gui_get_vbox (gradient_tool->gui)),
+                      editor, FALSE, TRUE, 0);
+
+  /* the main table */
+  table = gtk_table_new (1, 2, FALSE);
+  gtk_table_set_row_spacings (GTK_TABLE (table), 4);
+  gtk_table_set_col_spacings (GTK_TABLE (table), 4);
+  gtk_box_pack_start (GTK_BOX (editor), table, FALSE, TRUE, 0);
+  gtk_widget_show (table);
+
+  /* the position label */
+  label = gtk_label_new (_("Position:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row, row + 1,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  /* the position size entry */
+  gradient_tool->stop_se =
+  se                     = gimp_size_entry_new (1, GIMP_UNIT_PERCENT, "%a",
+                                                FALSE, TRUE, FALSE, 6,
+                                                GIMP_SIZE_ENTRY_UPDATE_SIZE);
+  gimp_size_entry_show_unit_menu (GIMP_SIZE_ENTRY (se), FALSE);
+  gtk_table_attach (GTK_TABLE (table), se, 1, 2, row, row + 1,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (se);
+
+  g_signal_connect (se, "value-changed",
+                    G_CALLBACK (gimp_gradient_tool_editor_stop_se_value_changed),
+                    gradient_tool);
+
+  row++;
+
+  /* the color labels */
+  label = gtk_label_new (_("Left color:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row, row + 1,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  label = gtk_label_new (_("Right color:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row + 1, row + 2,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  /* the color entries table */
+  table2 = gtk_table_new (1, 2, FALSE);
+  gtk_table_set_row_spacings (GTK_TABLE (table2), 4);
+  gtk_table_set_col_spacings (GTK_TABLE (table2), 2);
+  gtk_table_attach (GTK_TABLE (table), table2, 1, 2, row, row + 2,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (table2);
+
+  /* the color entries chain button */
+  gradient_tool->stop_chain_button =
+  button                           = gimp_chain_button_new (GIMP_CHAIN_RIGHT);
+  gtk_table_attach (GTK_TABLE (table2), button, 1, 2, 0, 2,
+                    GTK_SHRINK | GTK_FILL,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    0, 0);
+  gtk_widget_show (button);
+
+  /* the color entries */
+  hbox = gimp_gradient_tool_editor_color_entry_new (
+    gradient_tool, _("Change Stop Color"), DIRECTION_LEFT, button,
+    &gradient_tool->stop_left_color_panel, &gradient_tool->stop_left_type_combo);
+  gtk_table_attach (GTK_TABLE (table2), hbox, 0, 1, 0, 1,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (hbox);
+
+  hbox = gimp_gradient_tool_editor_color_entry_new (
+    gradient_tool, _("Change Stop Color"), DIRECTION_RIGHT, button,
+    &gradient_tool->stop_right_color_panel, &gradient_tool->stop_right_type_combo);
+  gtk_table_attach (GTK_TABLE (table2), hbox, 0, 1, 1, 2,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (hbox);
+
+  row += 2;
+
+  /* the action buttons separator */
+  separator = gtk_hseparator_new ();
+  gtk_table_attach (GTK_TABLE (table), separator, 0, 2, row, row + 1,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (separator);
+
+  row++;
+
+  /* the delete button */
+  gimp_editor_add_button (GIMP_EDITOR (editor),
+                          GIMP_ICON_EDIT_DELETE, _("Delete stop"),
+                          NULL,
+                          G_CALLBACK (gimp_gradient_tool_editor_stop_delete_clicked),
+                          NULL, G_OBJECT (gradient_tool));
+}
+
+static void
+gimp_gradient_tool_editor_init_midpoint_gui (GimpGradientTool *gradient_tool)
+{
+  GtkWidget *editor;
+  GtkWidget *table;
+  GtkWidget *label;
+  GtkWidget *se;
+  GtkWidget *combo;
+  GtkWidget *separator;
+  gint       row = 0;
+
+  /* the stop editor */
+  gradient_tool->midpoint_editor =
+  editor                         = gimp_editor_new ();
+  gtk_box_pack_start (GTK_BOX (gimp_tool_gui_get_vbox (gradient_tool->gui)),
+                      editor, FALSE, TRUE, 0);
+
+  /* the main table */
+  table = gtk_table_new (1, 2, FALSE);
+  gtk_table_set_row_spacings (GTK_TABLE (table), 4);
+  gtk_table_set_col_spacings (GTK_TABLE (table), 4);
+  gtk_box_pack_start (GTK_BOX (editor), table, FALSE, TRUE, 0);
+  gtk_widget_show (table);
+
+  /* the position label */
+  label = gtk_label_new (_("Position:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row, row + 1,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  /* the position size entry */
+  gradient_tool->midpoint_se =
+  se                         = gimp_size_entry_new (1, GIMP_UNIT_PERCENT, "%a",
+                                                    FALSE, TRUE, FALSE, 6,
+                                                    GIMP_SIZE_ENTRY_UPDATE_SIZE);
+  gimp_size_entry_show_unit_menu (GIMP_SIZE_ENTRY (se), FALSE);
+  gtk_table_attach (GTK_TABLE (table), se, 1, 2, row, row + 1,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (se);
+
+  g_signal_connect (se, "value-changed",
+                    G_CALLBACK (gimp_gradient_tool_editor_midpoint_se_value_changed),
+                    gradient_tool);
+
+  row++;
+
+  /* the type label */
+  label = gtk_label_new (_("Blending:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row, row + 1,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  /* the type combo */
+  gradient_tool->midpoint_type_combo =
+  combo                              = gimp_enum_combo_box_new (GIMP_TYPE_GRADIENT_SEGMENT_TYPE);
+  gtk_table_attach (GTK_TABLE (table), combo, 1, 2, row, row + 1,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (combo);
+
+  g_signal_connect (combo, "changed",
+                    G_CALLBACK (gimp_gradient_tool_editor_midpoint_type_changed),
+                    gradient_tool);
+
+  row++;
+
+  /* the color label */
+  label = gtk_label_new (_("Coloring:"));
+  gtk_label_set_xalign (GTK_LABEL (label), 0.0);
+  gtk_table_attach (GTK_TABLE (table), label, 0, 1, row, row + 1,
+                    GTK_SHRINK | GTK_FILL, GTK_SHRINK, 0, 0);
+  gtk_widget_show (label);
+
+  /* the color combo */
+  gradient_tool->midpoint_color_combo =
+  combo                              = gimp_enum_combo_box_new (GIMP_TYPE_GRADIENT_SEGMENT_COLOR);
+  gtk_table_attach (GTK_TABLE (table), combo, 1, 2, row, row + 1,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (combo);
+
+  g_signal_connect (combo, "changed",
+                    G_CALLBACK (gimp_gradient_tool_editor_midpoint_color_changed),
+                    gradient_tool);
+
+  row++;
+
+  /* the action buttons separator */
+  separator = gtk_hseparator_new ();
+  gtk_table_attach (GTK_TABLE (table), separator, 0, 2, row, row + 1,
+                    GTK_SHRINK | GTK_FILL | GTK_EXPAND,
+                    GTK_SHRINK | GTK_FILL,
+                    0, 0);
+  gtk_widget_show (separator);
+
+  row++;
+
+  /* the new stop button */
+  gradient_tool->midpoint_new_stop_button =
+    gimp_editor_add_button (GIMP_EDITOR (editor),
+                            GIMP_ICON_DOCUMENT_NEW, _("New stop at midpoint"),
+                            NULL,
+                            G_CALLBACK (gimp_gradient_tool_editor_midpoint_new_stop_clicked),
+                            NULL, G_OBJECT (gradient_tool));
+
+  /* the center button */
+  gradient_tool->midpoint_center_button =
+    gimp_editor_add_button (GIMP_EDITOR (editor),
+                            GIMP_ICON_CENTER_HORIZONTAL, _("Center midpoint"),
+                            NULL,
+                            G_CALLBACK (gimp_gradient_tool_editor_midpoint_center_clicked),
+                            NULL, G_OBJECT (gradient_tool));
+}
+
+static void
+gimp_gradient_tool_editor_update_endpoint_gui (GimpGradientTool *gradient_tool,
+                                               gint              selection)
+{
+  GimpGradientOptions *options       = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpPaintOptions    *paint_options = GIMP_PAINT_OPTIONS (options);
+  GimpContext         *context       = GIMP_CONTEXT (options);
+  gboolean             editable;
+  GimpGradientSegment *seg;
+  const gchar         *title;
+  gdouble              x;
+  gdouble              y;
+  GimpRGB              color;
+  GimpGradientColor    color_type;
+
+  editable = gimp_gradient_tool_editor_is_gradient_editable (gradient_tool);
+
+  switch (selection)
+    {
+    case GIMP_TOOL_LINE_HANDLE_START:
+      g_object_get (gradient_tool->widget,
+                    "x1", &x,
+                    "y1", &y,
+                    NULL);
+      break;
+
+    case GIMP_TOOL_LINE_HANDLE_END:
+      g_object_get (gradient_tool->widget,
+                    "x2", &x,
+                    "y2", &y,
+                    NULL);
+      break;
+
+    default:
+      gimp_assert_not_reached ();
+    }
+
+  /* swap the endpoint handles, if necessary */
+  if (paint_options->gradient_options->gradient_reverse)
+    {
+      switch (selection)
+        {
+        case GIMP_TOOL_LINE_HANDLE_START:
+          selection = GIMP_TOOL_LINE_HANDLE_END;
+          break;
+
+        case GIMP_TOOL_LINE_HANDLE_END:
+          selection = GIMP_TOOL_LINE_HANDLE_START;
+          break;
+        }
+    }
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  switch (selection)
+    {
+    case GIMP_TOOL_LINE_HANDLE_START:
+      title = _("Start Endpoint");
+
+      gimp_gradient_segment_get_left_flat_color (gradient_tool->gradient, context,
+                                                 seg, &color);
+      color_type = seg->left_color_type;
+      break;
+
+    case GIMP_TOOL_LINE_HANDLE_END:
+      title = _("End Endpoint");
+
+      gimp_gradient_segment_get_right_flat_color (gradient_tool->gradient, context,
+                                                  seg, &color);
+      color_type = seg->right_color_type;
+      break;
+
+    default:
+      gimp_assert_not_reached ();
+    }
+
+  gimp_tool_gui_set_title (gradient_tool->gui, title);
+
+  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (gradient_tool->endpoint_se), 0, x);
+  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (gradient_tool->endpoint_se), 1, y);
+
+  gimp_color_button_set_color (
+    GIMP_COLOR_BUTTON (gradient_tool->endpoint_color_panel), &color);
+  gimp_int_combo_box_set_active (
+    GIMP_INT_COMBO_BOX (gradient_tool->endpoint_type_combo), color_type);
+
+  gtk_widget_set_sensitive (gradient_tool->endpoint_color_panel, editable);
+  gtk_widget_set_sensitive (gradient_tool->endpoint_type_combo,  editable);
+
+  gtk_widget_show (gradient_tool->endpoint_editor);
+}
+
+static void
+gimp_gradient_tool_editor_update_stop_gui (GimpGradientTool *gradient_tool,
+                                           gint              selection)
+{
+  GimpGradientOptions *options = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpContext         *context = GIMP_CONTEXT (options);
+  gboolean             editable;
+  GimpGradientSegment *seg;
+  gint                 index;
+  gchar               *title;
+  gdouble              min;
+  gdouble              max;
+  gdouble              value;
+  GimpRGB              left_color;
+  GimpGradientColor    left_color_type;
+  GimpRGB              right_color;
+  GimpGradientColor    right_color_type;
+
+  editable = gimp_gradient_tool_editor_is_gradient_editable (gradient_tool);
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  index = GPOINTER_TO_INT (
+    gimp_tool_line_get_sliders (GIMP_TOOL_LINE (gradient_tool->widget),
+                                NULL)[selection].data);
+
+  title = g_strdup_printf (_("Stop %d"), index + 1);
+
+  min   = seg->left;
+  max   = seg->next->right;
+  value = seg->right;
+
+  gimp_gradient_segment_get_right_flat_color (gradient_tool->gradient, context,
+                                              seg, &left_color);
+  left_color_type = seg->right_color_type;
+
+  gimp_gradient_segment_get_left_flat_color (gradient_tool->gradient, context,
+                                             seg->next, &right_color);
+  right_color_type = seg->next->left_color_type;
+
+  gimp_tool_gui_set_title (gradient_tool->gui, title);
+
+  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (gradient_tool->stop_se),
+                                         0, 100.0 * min, 100.0 * max);
+  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (gradient_tool->stop_se),
+                              0, 100.0 * value);
+
+  gimp_color_button_set_color (
+    GIMP_COLOR_BUTTON (gradient_tool->stop_left_color_panel), &left_color);
+  gimp_int_combo_box_set_active (
+    GIMP_INT_COMBO_BOX (gradient_tool->stop_left_type_combo), left_color_type);
+
+  gimp_color_button_set_color (
+    GIMP_COLOR_BUTTON (gradient_tool->stop_right_color_panel), &right_color);
+  gimp_int_combo_box_set_active (
+    GIMP_INT_COMBO_BOX (gradient_tool->stop_right_type_combo), right_color_type);
+
+  gtk_widget_set_sensitive (gradient_tool->stop_se,                editable);
+  gtk_widget_set_sensitive (gradient_tool->stop_left_color_panel,  editable);
+  gtk_widget_set_sensitive (gradient_tool->stop_left_type_combo,   editable);
+  gtk_widget_set_sensitive (gradient_tool->stop_right_color_panel, editable);
+  gtk_widget_set_sensitive (gradient_tool->stop_right_type_combo,  editable);
+  gtk_widget_set_sensitive (gradient_tool->stop_chain_button,      editable);
+  gtk_widget_set_sensitive (
+    GTK_WIDGET (gimp_editor_get_button_box (GIMP_EDITOR (gradient_tool->stop_editor))),
+    editable);
+
+  g_free (title);
+
+  gtk_widget_show (gradient_tool->stop_editor);
+}
+
+static void
+gimp_gradient_tool_editor_update_midpoint_gui (GimpGradientTool *gradient_tool,
+                                               gint              selection)
+{
+  gboolean                    editable;
+  const GimpGradientSegment  *seg;
+  gint                        index;
+  gchar                      *title;
+  gdouble                     min;
+  gdouble                     max;
+  gdouble                     value;
+  GimpGradientSegmentType     type;
+  GimpGradientSegmentColor    color;
+
+  editable = gimp_gradient_tool_editor_is_gradient_editable (gradient_tool);
+
+  seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, selection);
+
+  index = GPOINTER_TO_INT (
+    gimp_tool_line_get_sliders (GIMP_TOOL_LINE (gradient_tool->widget),
+                                NULL)[selection].data);
+
+  title = g_strdup_printf (_("Midpoint %d"), index + 1);
+
+  min   = seg->left;
+  max   = seg->right;
+  value = seg->middle;
+  type  = seg->type;
+  color = seg->color;
+
+  gimp_tool_gui_set_title (gradient_tool->gui, title);
+
+  gimp_size_entry_set_refval_boundaries (GIMP_SIZE_ENTRY (gradient_tool->midpoint_se),
+                                         0, 100.0 * min, 100.0 * max);
+  gimp_size_entry_set_refval (GIMP_SIZE_ENTRY (gradient_tool->midpoint_se),
+                              0, 100.0 * value);
+
+  gimp_int_combo_box_set_active (
+    GIMP_INT_COMBO_BOX (gradient_tool->midpoint_type_combo), type);
+
+  gimp_int_combo_box_set_active (
+    GIMP_INT_COMBO_BOX (gradient_tool->midpoint_color_combo), color);
+
+  gtk_widget_set_sensitive (gradient_tool->midpoint_new_stop_button,
+                            value > min + EPSILON && value < max - EPSILON);
+  gtk_widget_set_sensitive (gradient_tool->midpoint_center_button,
+                            fabs (value - (min + max) / 2.0) > EPSILON);
+
+  gtk_widget_set_sensitive (gradient_tool->midpoint_se,          editable);
+  gtk_widget_set_sensitive (gradient_tool->midpoint_type_combo,  editable);
+  gtk_widget_set_sensitive (gradient_tool->midpoint_color_combo, editable);
+  gtk_widget_set_sensitive (
+    GTK_WIDGET (gimp_editor_get_button_box (GIMP_EDITOR (gradient_tool->midpoint_editor))),
+    editable);
+
+  g_free (title);
+
+  gtk_widget_show (gradient_tool->midpoint_editor);
+}
+
+static void
+gimp_gradient_tool_editor_update_gui (GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions *options = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+
+  if (gradient_tool->gradient && gradient_tool->widget && ! options->instant)
+    {
+      gint selection;
+
+      selection =
+        gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+      if (selection != GIMP_TOOL_LINE_HANDLE_NONE)
+        {
+          if (! gradient_tool->gui)
+            {
+              GimpDisplayShell *shell;
+
+              shell = gimp_tool_widget_get_shell (gradient_tool->widget);
+
+              gradient_tool->gui =
+                gimp_tool_gui_new (GIMP_TOOL (gradient_tool)->tool_info,
+                                   NULL, NULL, NULL, NULL,
+                                   gtk_widget_get_screen (GTK_WIDGET (shell)),
+                                   gimp_widget_get_monitor (GTK_WIDGET (shell)),
+                                   TRUE,
+
+                                   _("_Close"), GTK_RESPONSE_CLOSE,
+
+                                   NULL);
+
+              gimp_tool_gui_set_shell (gradient_tool->gui, shell);
+              gimp_tool_gui_set_viewable (gradient_tool->gui,
+                                          GIMP_VIEWABLE (gradient_tool->gradient));
+              gimp_tool_gui_set_auto_overlay (gradient_tool->gui, TRUE);
+
+              g_signal_connect (gradient_tool->gui, "response",
+                                G_CALLBACK (gimp_gradient_tool_editor_gui_response),
+                                gradient_tool);
+
+              gimp_gradient_tool_editor_init_endpoint_gui (gradient_tool);
+              gimp_gradient_tool_editor_init_stop_gui     (gradient_tool);
+              gimp_gradient_tool_editor_init_midpoint_gui (gradient_tool);
+            }
+
+          gimp_gradient_tool_editor_block_handlers (gradient_tool);
+
+          if (gimp_gradient_tool_editor_handle_is_endpoint (gradient_tool, selection))
+            gimp_gradient_tool_editor_update_endpoint_gui (gradient_tool, selection);
+          else
+            gtk_widget_hide (gradient_tool->endpoint_editor);
+
+          if (gimp_gradient_tool_editor_handle_is_stop (gradient_tool, selection))
+            gimp_gradient_tool_editor_update_stop_gui (gradient_tool, selection);
+          else
+            gtk_widget_hide (gradient_tool->stop_editor);
+
+          if (gimp_gradient_tool_editor_handle_is_midpoint (gradient_tool, selection))
+            gimp_gradient_tool_editor_update_midpoint_gui (gradient_tool, selection);
+          else
+            gtk_widget_hide (gradient_tool->midpoint_editor);
+
+          gimp_gradient_tool_editor_unblock_handlers (gradient_tool);
+
+          gimp_tool_gui_show (gradient_tool->gui);
+
+          return;
+        }
+    }
+
+  if (gradient_tool->gui)
+    gimp_tool_gui_hide (gradient_tool->gui);
+}
+
+static GradientInfo *
+gimp_gradient_tool_editor_gradient_info_new (GimpGradientTool *gradient_tool)
+{
+  GradientInfo *info = g_slice_new (GradientInfo);
+
+  info->start_x         = gradient_tool->start_x;
+  info->start_y         = gradient_tool->start_y;
+  info->end_x           = gradient_tool->end_x;
+  info->end_y           = gradient_tool->end_y;
+
+  info->gradient        = NULL;
+
+  info->added_handle    = GIMP_TOOL_LINE_HANDLE_NONE;
+  info->removed_handle  = GIMP_TOOL_LINE_HANDLE_NONE;
+  info->selected_handle = GIMP_TOOL_LINE_HANDLE_NONE;
+
+  return info;
+}
+
+static void
+gimp_gradient_tool_editor_gradient_info_free (GradientInfo *info)
+{
+  if (info->gradient)
+    g_object_unref (info->gradient);
+
+  g_slice_free (GradientInfo, info);
+}
+
+static void
+gimp_gradient_tool_editor_gradient_info_apply (GimpGradientTool   *gradient_tool,
+                                               const GradientInfo *info,
+                                               gboolean            set_selection)
+{
+  gint selection;
+
+  gimp_assert (gradient_tool->widget   != NULL);
+  gimp_assert (gradient_tool->gradient != NULL);
+
+  /* pick the handle to select */
+  if (info->gradient)
+    {
+      if (info->removed_handle != GIMP_TOOL_LINE_HANDLE_NONE)
+        {
+          /* we're undoing a stop-deletion or midpoint-to-stop operation;
+           * select the removed handle
+           */
+          selection = info->removed_handle;
+        }
+      else if (info->added_handle != GIMP_TOOL_LINE_HANDLE_NONE)
+        {
+          /* we're undoing a stop addition operation */
+          gimp_assert (gimp_gradient_tool_editor_handle_is_stop (gradient_tool,
+                                                                 info->added_handle));
+
+          selection =
+            gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+          /* if the selected handle is a stop... */
+          if (gimp_gradient_tool_editor_handle_is_stop (gradient_tool, selection))
+            {
+              /* if the added handle is selected, clear the selection */
+              if (selection == info->added_handle)
+                selection = GIMP_TOOL_LINE_HANDLE_NONE;
+              /* otherwise, keep the currently selected stop, possibly
+               * adjusting its handle index
+               */
+              else if (selection > info->added_handle)
+                selection--;
+            }
+          /* otherwise, if the selected handle is a midpoint... */
+          else if (gimp_gradient_tool_editor_handle_is_midpoint (gradient_tool, selection))
+            {
+              const GimpControllerSlider *sliders;
+              gint                        seg_i;
+
+              sliders =
+                gimp_tool_line_get_sliders (GIMP_TOOL_LINE (gradient_tool->widget),
+                                            NULL);
+
+              seg_i = GPOINTER_TO_INT (sliders[selection].data);
+
+              /* if the midpoint belongs to one of the two segments incident to
+               * the added stop, clear the selection
+               */
+              if (seg_i == info->added_handle ||
+                  seg_i == info->added_handle + 1)
+                {
+                  selection = GIMP_TOOL_LINE_HANDLE_NONE;
+                }
+              /* otherwise, keep the currently selected stop, adjusting its
+               * handle index
+               */
+              else
+                {
+                  /* midpoint handles follow stop handles; since we removed a
+                   * stop, we must decrement the handle index
+                   */
+                  selection--;
+
+                  if (seg_i > info->added_handle)
+                    selection--;
+                }
+            }
+          /* otherwise, don't change the selection */
+          else
+            {
+              set_selection = FALSE;
+            }
+        }
+      else if (info->selected_handle != GIMP_TOOL_LINE_HANDLE_NONE)
+        {
+          /* we're undoing a property change operation; select the handle
+           * corresponding to the affected object
+           */
+          selection = info->selected_handle;
+        }
+      else
+        {
+          /* something went wrong... */
+          g_warn_if_reached ();
+
+          set_selection = FALSE;
+        }
+    }
+  else if ((info->start_x != gradient_tool->start_x  ||
+            info->start_y != gradient_tool->start_y) &&
+           (info->end_x   == gradient_tool->end_x    &&
+            info->end_y   == gradient_tool->end_y))
+    {
+      /* we're undoing a start-endpoint move operation; select the start
+       * endpoint
+       */
+      selection = GIMP_TOOL_LINE_HANDLE_START;
+    }
+  else if ((info->end_x   != gradient_tool->end_x    ||
+            info->end_y   != gradient_tool->end_y)   &&
+           (info->start_x == gradient_tool->start_x  &&
+            info->start_y == gradient_tool->start_y))
+
+    {
+      /* we're undoing am end-endpoint move operation; select the end
+       * endpoint
+       */
+      selection = GIMP_TOOL_LINE_HANDLE_END;
+    }
+  else
+    {
+      /* we're undoing a line move operation; don't change the selection */
+      set_selection = FALSE;
+    }
+
+  gimp_gradient_tool_editor_block_handlers (gradient_tool);
+
+  g_object_set (gradient_tool->widget,
+                "x1", info->start_x,
+                "y1", info->start_y,
+                "x2", info->end_x,
+                "y2", info->end_y,
+                NULL);
+
+  if (info->gradient)
+    {
+      gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+      gimp_data_copy (GIMP_DATA (gradient_tool->gradient),
+                      GIMP_DATA (info->gradient));
+
+      gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+    }
+
+  if (set_selection)
+    {
+      gimp_tool_line_set_selection (GIMP_TOOL_LINE (gradient_tool->widget),
+                                    selection);
+    }
+
+  gimp_gradient_tool_editor_update_gui (gradient_tool);
+
+  gimp_gradient_tool_editor_unblock_handlers (gradient_tool);
+}
+
+static gboolean
+gimp_gradient_tool_editor_gradient_info_is_trivial (GimpGradientTool   *gradient_tool,
+                                                    const GradientInfo *info)
+{
+  const GimpGradientSegment *seg1;
+  const GimpGradientSegment *seg2;
+
+  if (info->start_x != gradient_tool->start_x ||
+      info->start_y != gradient_tool->start_y ||
+      info->end_x   != gradient_tool->end_x   ||
+      info->end_y   != gradient_tool->end_y)
+    {
+      return FALSE;
+    }
+
+  if (info->gradient)
+    {
+      for (seg1 = info->gradient->segments, seg2 = gradient_tool->gradient->segments;
+           seg1 && seg2;
+           seg1 = seg1->next, seg2 = seg2->next)
+        {
+          if (memcmp (seg1, seg2, G_STRUCT_OFFSET (GimpGradientSegment, prev)))
+            return FALSE;
+        }
+
+      if (seg1 || seg2)
+        return FALSE;
+    }
+
+  return TRUE;
+}
+
+
+/*  public functions  */
+
+void
+gimp_gradient_tool_editor_options_notify (GimpGradientTool *gradient_tool,
+                                          GimpToolOptions  *options,
+                                          const GParamSpec *pspec)
+{
+  if (! strcmp (pspec->name, "modify-active"))
+    {
+      gimp_gradient_tool_editor_update_sliders (gradient_tool);
+      gimp_gradient_tool_editor_update_gui (gradient_tool);
+    }
+  else if (! strcmp (pspec->name, "gradient-reverse"))
+    {
+      gimp_gradient_tool_editor_update_sliders (gradient_tool);
+
+      /* if an endpoint is selected, swap the selected endpoint */
+      if (gradient_tool->widget)
+        {
+          gint selection;
+
+          selection =
+            gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+          switch (selection)
+            {
+            case GIMP_TOOL_LINE_HANDLE_START:
+              gimp_tool_line_set_selection (GIMP_TOOL_LINE (gradient_tool->widget),
+                                            GIMP_TOOL_LINE_HANDLE_END);
+              break;
+
+            case GIMP_TOOL_LINE_HANDLE_END:
+              gimp_tool_line_set_selection (GIMP_TOOL_LINE (gradient_tool->widget),
+                                            GIMP_TOOL_LINE_HANDLE_START);
+              break;
+            }
+        }
+    }
+  else if (gradient_tool->render_node &&
+           gegl_node_find_property (gradient_tool->render_node, pspec->name))
+    {
+      gimp_gradient_tool_editor_update_sliders (gradient_tool);
+    }
+}
+
+void
+gimp_gradient_tool_editor_start (GimpGradientTool *gradient_tool)
+{
+  g_signal_connect (gradient_tool->widget, "can-add-slider",
+                    G_CALLBACK (gimp_gradient_tool_editor_line_can_add_slider),
+                    gradient_tool);
+  g_signal_connect (gradient_tool->widget, "add-slider",
+                    G_CALLBACK (gimp_gradient_tool_editor_line_add_slider),
+                    gradient_tool);
+  g_signal_connect (gradient_tool->widget, "prepare-to-remove-slider",
+                    G_CALLBACK (gimp_gradient_tool_editor_line_prepare_to_remove_slider),
+                    gradient_tool);
+  g_signal_connect (gradient_tool->widget, "remove-slider",
+                    G_CALLBACK (gimp_gradient_tool_editor_line_remove_slider),
+                    gradient_tool);
+  g_signal_connect (gradient_tool->widget, "selection-changed",
+                    G_CALLBACK (gimp_gradient_tool_editor_line_selection_changed),
+                    gradient_tool);
+  g_signal_connect (gradient_tool->widget, "handle-clicked",
+                    G_CALLBACK (gimp_gradient_tool_editor_line_handle_clicked),
+                    gradient_tool);
+}
+
+void
+gimp_gradient_tool_editor_halt (GimpGradientTool *gradient_tool)
+{
+  g_clear_object (&gradient_tool->gui);
+
+  gradient_tool->edit_count = 0;
+
+  if (gradient_tool->undo_stack)
+    {
+      g_slist_free_full (gradient_tool->undo_stack,
+                         (GDestroyNotify) gimp_gradient_tool_editor_gradient_info_free);
+      gradient_tool->undo_stack = NULL;
+    }
+
+  if (gradient_tool->redo_stack)
+    {
+      g_slist_free_full (gradient_tool->redo_stack,
+                         (GDestroyNotify) gimp_gradient_tool_editor_gradient_info_free);
+      gradient_tool->redo_stack = NULL;
+    }
+
+  if (gradient_tool->flush_idle_id)
+    {
+      g_source_remove (gradient_tool->flush_idle_id);
+      gradient_tool->flush_idle_id = 0;
+    }
+}
+
+gboolean
+gimp_gradient_tool_editor_line_changed (GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions        *options       = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpPaintOptions           *paint_options = GIMP_PAINT_OPTIONS (options);
+  gdouble                     offset        = options->offset / 100.0;
+  const GimpControllerSlider *sliders;
+  gint                        n_sliders;
+  gint                        i;
+  GimpGradientSegment        *seg;
+  gboolean                    changed       = FALSE;
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return FALSE;
+
+  if (! gradient_tool->gradient || offset == 1.0)
+    return FALSE;
+
+  sliders = gimp_tool_line_get_sliders (GIMP_TOOL_LINE (gradient_tool->widget),
+                                        &n_sliders);
+
+  if (n_sliders == 0)
+    return FALSE;
+
+  /* update the midpoints first, since moving the gradient stops may change the
+   * gradient's midpoints w.r.t. the sliders, but not the other way around.
+   */
+  for (seg = gradient_tool->gradient->segments, i = n_sliders / 2;
+       seg;
+       seg = seg->next, i++)
+    {
+      gdouble value;
+
+      value = sliders[i].value;
+
+      /* adjust slider value according to the offset */
+      value = (value - offset) / (1.0 - offset);
+
+      /* flip the slider value, if necessary */
+      if (paint_options->gradient_options->gradient_reverse)
+        value = 1.0 - value;
+
+      if (fabs (value - seg->middle) > EPSILON)
+        {
+          if (! changed)
+            {
+              gimp_gradient_tool_editor_start_edit (gradient_tool);
+              gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+              /* refetch the segment, since the gradient might have changed */
+              seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, i);
+
+              changed = TRUE;
+            }
+
+          seg->middle = value;
+        }
+    }
+
+  /* update the gradient stops */
+  for (seg = gradient_tool->gradient->segments, i = 0;
+       seg->next;
+       seg = seg->next, i++)
+    {
+      gdouble value;
+
+      value = sliders[i].value;
+
+      /* adjust slider value according to the offset */
+      value = (value - offset) / (1.0 - offset);
+
+      /* flip the slider value, if necessary */
+      if (paint_options->gradient_options->gradient_reverse)
+        value = 1.0 - value;
+
+      if (fabs (value - seg->right) > EPSILON)
+        {
+          if (! changed)
+            {
+              gimp_gradient_tool_editor_start_edit (gradient_tool);
+              gimp_gradient_tool_editor_freeze_gradient (gradient_tool);
+
+              /* refetch the segment, since the gradient might have changed */
+              seg = gimp_gradient_tool_editor_handle_get_segment (gradient_tool, i);
+
+              changed = TRUE;
+            }
+
+          gimp_gradient_segment_range_compress (gradient_tool->gradient,
+                                                seg, seg,
+                                                seg->left, value);
+          gimp_gradient_segment_range_compress (gradient_tool->gradient,
+                                                seg->next, seg->next,
+                                                value, seg->next->right);
+        }
+    }
+
+  if (changed)
+    {
+      gimp_gradient_tool_editor_thaw_gradient (gradient_tool);
+      gimp_gradient_tool_editor_end_edit (gradient_tool, FALSE);
+    }
+
+  gimp_gradient_tool_editor_update_gui (gradient_tool);
+
+  return changed;
+}
+
+void
+gimp_gradient_tool_editor_fg_bg_changed (GimpGradientTool *gradient_tool)
+{
+  gimp_gradient_tool_editor_update_gui (gradient_tool);
+}
+
+void
+gimp_gradient_tool_editor_gradient_dirty (GimpGradientTool *gradient_tool)
+{
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  gimp_gradient_tool_editor_purge_gradient (gradient_tool);
+}
+
+void
+gimp_gradient_tool_editor_gradient_changed (GimpGradientTool *gradient_tool)
+{
+  GimpGradientOptions *options = GIMP_GRADIENT_TOOL_GET_OPTIONS (gradient_tool);
+  GimpContext         *context = GIMP_CONTEXT (options);
+
+  if (options->modify_active_frame)
+    {
+      gtk_widget_set_sensitive (options->modify_active_frame,
+                                gradient_tool->gradient !=
+                                gimp_gradients_get_custom (context->gimp));
+    }
+
+  if (options->modify_active_hint)
+    {
+      gtk_widget_set_visible (options->modify_active_hint,
+                              gradient_tool->gradient &&
+                              ! gimp_data_is_writable (GIMP_DATA (gradient_tool->gradient)));
+    }
+
+  if (gimp_gradient_tool_editor_are_handlers_blocked (gradient_tool))
+    return;
+
+  gimp_gradient_tool_editor_purge_gradient (gradient_tool);
+}
+
+const gchar *
+gimp_gradient_tool_editor_can_undo (GimpGradientTool *gradient_tool)
+{
+  if (! gradient_tool->undo_stack || gradient_tool->edit_count > 0)
+    return NULL;
+
+  return _("Gradient Step");
+}
+
+const gchar *
+gimp_gradient_tool_editor_can_redo (GimpGradientTool *gradient_tool)
+{
+  if (! gradient_tool->redo_stack || gradient_tool->edit_count > 0)
+    return NULL;
+
+  return _("Gradient Step");
+}
+
+gboolean
+gimp_gradient_tool_editor_undo (GimpGradientTool *gradient_tool)
+{
+  GimpTool  *tool = GIMP_TOOL (gradient_tool);
+  GradientInfo *info;
+  GradientInfo *new_info;
+
+  gimp_assert (gradient_tool->undo_stack != NULL);
+  gimp_assert (gradient_tool->edit_count == 0);
+
+  info = gradient_tool->undo_stack->data;
+
+  new_info = gimp_gradient_tool_editor_gradient_info_new (gradient_tool);
+
+  if (info->gradient)
+    {
+      new_info->gradient =
+        GIMP_GRADIENT (gimp_data_duplicate (GIMP_DATA (gradient_tool->gradient)));
+
+      /* swap the added and removed handles, so that gradient_info_apply() does
+       * the right thing on redo
+       */
+      new_info->added_handle    = info->removed_handle;
+      new_info->removed_handle  = info->added_handle;
+      new_info->selected_handle = info->selected_handle;
+    }
+
+  gradient_tool->undo_stack = g_slist_remove (gradient_tool->undo_stack, info);
+  gradient_tool->redo_stack = g_slist_prepend (gradient_tool->redo_stack, new_info);
+
+  gimp_gradient_tool_editor_gradient_info_apply (gradient_tool, info, TRUE);
+  gimp_gradient_tool_editor_gradient_info_free (info);
+
+  /* the initial state of the gradient tool is not useful; we might as well halt */
+  if (! gradient_tool->undo_stack)
+    gimp_tool_control (tool, GIMP_TOOL_ACTION_HALT, tool->display);
+
+  return TRUE;
+}
+
+gboolean
+gimp_gradient_tool_editor_redo (GimpGradientTool *gradient_tool)
+{
+  GradientInfo *info;
+  GradientInfo *new_info;
+
+  gimp_assert (gradient_tool->redo_stack != NULL);
+  gimp_assert (gradient_tool->edit_count == 0);
+
+  info = gradient_tool->redo_stack->data;
+
+  new_info = gimp_gradient_tool_editor_gradient_info_new (gradient_tool);
+
+  if (info->gradient)
+    {
+      new_info->gradient =
+        GIMP_GRADIENT (gimp_data_duplicate (GIMP_DATA (gradient_tool->gradient)));
+
+      /* swap the added and removed handles, so that gradient_info_apply() does
+       * the right thing on undo
+       */
+      new_info->added_handle    = info->removed_handle;
+      new_info->removed_handle  = info->added_handle;
+      new_info->selected_handle = info->selected_handle;
+    }
+
+  gradient_tool->redo_stack = g_slist_remove (gradient_tool->redo_stack, info);
+  gradient_tool->undo_stack = g_slist_prepend (gradient_tool->undo_stack, new_info);
+
+  gimp_gradient_tool_editor_gradient_info_apply (gradient_tool, info, TRUE);
+  gimp_gradient_tool_editor_gradient_info_free (info);
+
+  return TRUE;
+}
+
+void
+gimp_gradient_tool_editor_start_edit (GimpGradientTool *gradient_tool)
+{
+  if (gradient_tool->edit_count++ == 0)
+    {
+      GradientInfo *info;
+
+      info = gimp_gradient_tool_editor_gradient_info_new (gradient_tool);
+
+      gradient_tool->undo_stack = g_slist_prepend (gradient_tool->undo_stack, info);
+
+      /*  update the undo actions / menu items  */
+      if (! gradient_tool->flush_idle_id)
+        {
+          gradient_tool->flush_idle_id =
+            g_idle_add ((GSourceFunc) gimp_gradient_tool_editor_flush_idle,
+                        gradient_tool);
+        }
+    }
+}
+
+void
+gimp_gradient_tool_editor_end_edit (GimpGradientTool *gradient_tool,
+                                    gboolean          cancel)
+{
+  /* can happen when halting using esc */
+  if (gradient_tool->edit_count == 0)
+    return;
+
+  if (--gradient_tool->edit_count == 0)
+    {
+      GradientInfo *info = gradient_tool->undo_stack->data;
+
+      info->selected_handle =
+        gimp_tool_line_get_selection (GIMP_TOOL_LINE (gradient_tool->widget));
+
+      if (cancel ||
+          gimp_gradient_tool_editor_gradient_info_is_trivial (gradient_tool, info))
+        {
+          /* if the edit is canceled, or if nothing changed, undo the last
+           * step
+           */
+          gimp_gradient_tool_editor_gradient_info_apply (gradient_tool, info, FALSE);
+
+          gradient_tool->undo_stack = g_slist_remove (gradient_tool->undo_stack,
+                                                   info);
+          gimp_gradient_tool_editor_gradient_info_free (info);
+        }
+      else
+        {
+          /* otherwise, blow the redo stack */
+          g_slist_free_full (gradient_tool->redo_stack,
+                             (GDestroyNotify) gimp_gradient_tool_editor_gradient_info_free);
+          gradient_tool->redo_stack = NULL;
+        }
+
+      /*  update the undo actions / menu items  */
+      if (! gradient_tool->flush_idle_id)
+        {
+          gradient_tool->flush_idle_id =
+            g_idle_add ((GSourceFunc) gimp_gradient_tool_editor_flush_idle,
+                        gradient_tool);
+        }
+    }
+}