Can we please use symbolic constants for window style?
Why are we bothering with WS_VISIBLE in the tests? It can't prove anything since we strip it out anyway when checking. (I'm not sure why we do that, but.) This also makes the tests confusing to read...
The style management bothers me, because it doesn't seem very declarative. We believe the style the application sets here is the one they want to restore, except we don't believe it about WS_POPUP | WS_SYSMENU? Why not?