If the window does not have an alpha channel, we now set every pixel's
alpha to 0xFF. This is needed by the WindowServer when it does alpha
blending, there used to be some weird stuff happening on overlapping
windows.
Also when we are invalidating a region with width of the whole window,
we can do a single memcpy instead of a memcpy for each row separately.
Bananymous
3fb903d991