Dragging a floating QDockWidget from far left of the title bar doesn't allow you to dock the QDockWidget in its parent QMainWindow

This bug can be seen in QT Designer. If you float the WidgetBox (QDockWidget) and click on the far left of the title bar just before where the cursor changes to a resize handle, then you won't be able to dock the WidgetBox in the MainWindow. This same problem can be seen on any application using floatable/dockable QDockWidgets.