1. (Windows) Improve the window updating logic to eliminate the flickering black flashes that previously appeared during certain window operations, particularly resizing the window or updating buttons.
2. (Windows) A new command line switch -dbw can be specified under XP to invoke "double buffered windows" mode, which is an XP feature that claims to make Window operations smoother and with less flicker. Our tests have been inconclusive; it slows down some operations, particularly button drawing on slower PCs, but does seem to improve window painting smoothness somewhat. Try it for yourself. The switch has no effect under W2000 and prior.
