This has been there probably forever, what is needed is for the Windows
thread to keep track of what buttons and keys it has said are down to X11,
and when it gets an app deactivate message to send XK_KEYUP and XK_BUTTONUP
or whatever. That would fix the scrollbar in xterm too which follows your
mouse if you leave the window while dragging and run another Windoze app.
Until then you should be good just hitting return or clicking thw
aruck mouse button in any X window if you get stuck in a loop...