_SCREENCLICK will punch the mouse anywhere on the screen, even outside your window.
I'm using it to click the minimize button. I needed _SCREENX, _SCREENY, and_WIDTH
to compute where to click. Some situations may need the use of _HEIGHT, _DESKTOPWIDTH,
or _DESKTOPHEIGHT.
I have no clue how to stuff the keyboard buffer, tho clearly you can change the focus
to some other program with the above.