Instead of using GetKeyWait(), we directly call into an internal OS
function, which avoids the need to press a key before we can redraw over
the OS banner and VRAM when coming back. The disassembly to locate the
function was developed by Dr-Carlos.
We still have to redraw when coming back; getkey() will do it by
dupdate() by default, and it that's not a possibility for the
application an option to receive a special event and handle it manually
is provided.