Made DragAndDropContainer force mouse-cursor updates to help when using modifier keys to change the drag mode.

modules/juce_gui_basics/mouse/juce_DragAndDropContainer.cpp

@@ -154,10 +154,14 @@ public:
             else if (now > lastTimeOverTarget + RelativeTime::milliseconds (700))
                 checkForExternalDrag (details, screenPos);
         }
+
+        forceMouseCursorUpdate();
     }
 
     void timerCallback() override
     {
+        forceMouseCursorUpdate();
+
         if (sourceDetails.sourceComponent == nullptr)
         {
             delete this;
@@ -201,6 +205,11 @@ private:
     bool hasCheckedForExternalDrag;
     Time lastTimeOverTarget;
 
+    void forceMouseCursorUpdate()
+    {
+        Desktop::getInstance().getMainMouseSource().forceMouseCursorUpdate();
+    }
+
     DragAndDropTarget* getCurrentlyOver() const noexcept
     {
         return dynamic_cast <DragAndDropTarget*> (currentlyOverComp.get());

modules/juce_gui_basics/mouse/juce_DragAndDropContainer.h

@@ -110,7 +110,7 @@ public:
         It's useful when a component wants to call startDragging but doesn't know
         the DragAndDropContainer it should to use.
 
-        Obviously this may return 0 if it doesn't find a suitable component.
+        Obviously this may return nullptr if it doesn't find a suitable component.
     */
     static DragAndDropContainer* findParentDragContainerFor (Component* childComponent);