The fix for RFE 4387938 broke DnD on Solaris, Linux, and Windows.
MMouseDragGestureRecognizer fails to recognize a drag gesture,
since an assertion in mapDragOperationFromModifiers() doesn't allow
drag if the event modifiers include something other than the old mouse
button modifiers and key modifiers. Now event modifiers include new
mouse button modifiers, so this assertion fails.
As a result a drag cannot be initiated from Java drag source.