In Windows, dropActionChanged() method of
DropTargetListener is called when the user drags over
the drop target, even though the drop action is not changed,
when Drag-n-Drop is performed.

How to reproduce the Bug? -------->

Retrieve all files from the attachment and put it
in a single directory.
Compile all the files.
Run DnDSample.
You will see a Button on a Red Canvas.
Drag the Button and drop it on the Target Frame.

In the prompt if "Inside dropActionChanged() of Target"
is displayed even without changing the drop action,
the bug is reproduced.