[PATCH v2 1/6] d3d8/tests: Test for window changes when it's not active.

[Gabriel Ivăncescu]

Looks like d3d8 is unique; unlike d3d9ex, it checks if the foreground 
window belongs to the thread, where d3d9ex explicitly checks for 
focus_window instead.

ddraw is like d3d9ex where it checks its window explicitly, but it 
differs from both d3d8 and d3d9ex in that it treats an invisible window 
as "not active" and doesn't do changes—both d3d8 and d3d9ex do changes 
if the window is invisible.