win32: mouse-drag events not delivered when mouse moves outside of window bounds

On win32, it appears that with some components (specifically window subclasses)
mouse-drag events are only delivered if the mouse is within the bounds of the
window - once the mouse moves out, the events stop coming. This is not correct
behavior - mouse-drags should continue to be delivered until a mouse-released
event occurs (regardless of the mouse position).

This problem can be seen running the JCK test, EventTest2:

Bring up the Dialog window.
Click the mouse inside it and start dragging...you'll notice that events stop
coming when mouse moves outsdie of window's bounds. Also - if you move the
mouse into a different window, that different window will get the drag
events instead of the original window where the first drag originated (again,
this is incorrect behavior for drags).

Note that the dragging seems to work appropriately when the first drag is
initiated on a *Panel* (choose "panel" from the choice in the test to see
this working correctly).