switched it to buffered input, and the pause key seems to be properly
cooked, so I don't need to look for it with WM_KEYDOWN/UP. Tab doesn't
need to be special-cased either, because buffered input never passes on
the Tab key when you press Alt+Tab. I have no idea why I special-cased
Num Lock, but it seems to be working fine. By setting the exclusive mode
to background, I can also avoid special code for releasing all keys when
the window loses focus, because I'll still receive those events while the
window is in the background.
SVN r1613 (trunk)
