When we temporarily disable the screen (e.g. during TermMessage or
RunInteractiveShell), if the mouse is pressed when the screen is still
active and then released when the screen is already stopped, we aren't
able to catch this mouse release event, so we erroneously think that the
mouse is still pressed after the screen is restarted. This results in
wrong behavior due to a mouse press event treated as a mouse move event,
e.g. upon the left button click we see an unexpected text selection.
So need to reset the mouse release state to "released" after restarting
the screen, assuming it is always released when the screen is restarted.
If screen.Redraw() is called very quickly after a key or mouse event,
it may send the redraw event while micro is not waiting for it but
still processing the key or mouse event. Since drawChan is non-buffered
and at the same time non-blocking, this redraw event will be simply lost,
so the screen content will not be up-to-date.
