In Windows MousePressed, MouseReleased, MouseClicked are not triggered by scrollbar for middle mouse button when left mouse button is down.

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

Run this sample code. You would see a frame with Scrollbar in North Side.
Press the Left mouse button on the Scrollbar and keep it pressed for some
time say 20sec.Then Press Middle Mouse Button.Check whether MouseEvents -
Mouse Pressed,MouseClicked,Mouse Released are triggered for middle mouse button.