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diff --git a/canvas/inc/base/disambiguationhelper.hxx b/canvas/inc/base/disambiguationhelper.hxx
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * 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/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#pragma once
+
+#include <com/sun/star/lang/EventObject.hpp>
+#include <osl/mutex.hxx>
+
+
+/* Definition of the DisambiguationHelper class */
+
+namespace canvas
+{
+    /** Base class, initializing its own baseclass with m_aMutex.
+
+        This is necessary to make the CanvasBase, GraphicDeviceBase,
+        etc. classes freely combinable - letting them perform this
+        initialization would prohibit deriving e.g. CanvasBase from
+        GraphicDeviceBase.
+
+        On top of that, disambiguates XEventListener::disposing and
+        WeakComponentImplHelper::disposing.
+
+        Having two virtual methods with the same name, and not
+        overriding them in every derived class, will hide one of
+        them. Later trying to override the same method, will generate
+        a new vtable slot, and lead to very hard to spot errors.
+     */
+    template< class Base > class DisambiguationHelper : public Base
+    {
+    protected:
+        /** Construct DisambiguationHelper
+
+            This method is the whole purpose of this template:
+            initializing a base class with the provided m_aMutex
+            member (the WeakComponentImplHelper templates need that,
+            as they require the lifetime of the mutex to extend
+            theirs).
+         */
+        DisambiguationHelper() :
+            Base( m_aMutex )
+        {
+        }
+
+        virtual void disposeThis()
+        {}
+        /// @throws css::uno::RuntimeException
+        virtual void disposeEventSource( const css::lang::EventObject& )
+        {}
+
+        mutable ::osl::Mutex m_aMutex;
+
+    private:
+        virtual void SAL_CALL disposing() override
+        { disposeThis(); }
+
+        virtual void SAL_CALL disposing( const css::lang::EventObject& Source ) override
+        { disposeEventSource(Source); }
+
+    };
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */