TreeView: Allow built-in mouse handling to be enabled/disabled for custom components

modules/juce_gui_basics/widgets/juce_TreeView.cpp

@@ -344,7 +344,7 @@ public:
                 auto newComp = std::make_unique<ItemComponent> (*treeItem);
 
                 addAndMakeVisible (*newComp);
-                newComp->addMouseListener (this, false);
+                newComp->addMouseListener (this, treeItem->customComponentUsesTreeViewMouseHandler());
                 componentsToKeep.insert (newComp.get());
 
                 itemComponents.push_back (std::move (newComp));

modules/juce_gui_basics/widgets/juce_TreeView.h

@@ -363,6 +363,13 @@ public:
     /** Draws the line that extends vertically up towards one of its parents, or down to one of its children. */
     virtual void paintVerticalConnectingLine (Graphics&, const Line<float>& line);
 
+    /** This should return true if you want to use a custom component, and also use
+        the TreeView's built-in mouse handling support, enabling drag-and-drop,
+        itemClicked() and itemDoubleClicked(); return false if the component should
+        consume all mouse clicks.
+    */
+    virtual bool customComponentUsesTreeViewMouseHandler() const     { return false; }
+
     /** Called when the user clicks on this item.
 
         If you're using createItemComponent() to create a custom component for the