user32/tests: Add test for SetFocus() (with few todo)(Try 2).

[Sergey Guralnik]

Alexandre Julliard writes:
> Not really. If you want to test purely the Wine behavior, then you
> shouldn't be waiting for window manager events. If the window manager 
> is
> involved then you can't guarantee that a given window will always get
> focus.
> If your app breaks because the window manager doesn't give it focus 
> at a
> certain point, then pretty much the only solution is to change the wm
> policy, or use a different wm.

Thanks for explanations.