1 files changed, 40 insertions, 0 deletions
diff --git a/comm/mail/components/im/messages/mail/inline.js b/comm/mail/components/im/messages/mail/inline.js
new file mode 100644
index 0000000000..a6e7f72302
--- /dev/null
+++ b/comm/mail/components/im/messages/mail/inline.js
@@ -0,0 +1,40 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+function checkNewText(target) {
+  if (target.className == "event-row") {
+    let parent = target.closest(".event");
+    // We need to start a group with this element if there are at least 4
+    // system messages and they aren't already grouped.
+    if (
+      !parent?.grouped &&
+      parent?.querySelector(".event-row:nth-of-type(4)")
+    ) {
+      let toggle = document.createElement("div");
+      toggle.className = "eventToggle";
+      toggle.addEventListener("click", event => {
+        toggle.closest(".event").classList.toggle("hide-children");
+      });
+      parent.insertBefore(
+        toggle,
+        parent.querySelector(".event-row:nth-of-type(2)")
+      );
+      parent.classList.add("hide-children");
+      parent.grouped = true;
+    }
+  }
+}
+
+new MutationObserver(function (aMutations) {
+  for (let mutation of aMutations) {
+    for (let node of mutation.addedNodes) {
+      if (node instanceof HTMLElement) {
+        checkNewText(node);
+      }
+    }
+  }
+}).observe(document.getElementById("ibcontent"), {
+  childList: true,
+  subtree: true,
+});