changed locking to screen so that keys no longer count (only
mouse buttons and scroll lock toggled on). This is to deal
with the unreliability of key event reporting which can leave
us locked to a screen with no key physically pressed. The
result of this is that clients get key repeats and releases
without the corresponding key press. CKeyState handles this
by discarding repeat/release events on keys it hasn't seen go
down. Also made a few other minor fixes to win32 keyboard
handling.
