Popups not using wxPU_CONTAINS_CONTROLS were not automatically dismissed
at all any longer, as the only auto-dismissal mechanism related on
getting WM_ACTIVATE, which they never did, so implement a different
logic for dismissing them: do it on any change of focus and also any
mouse press (but not move and not key press neither).
This will allow not using wxPU_CONTAINS_CONTROLS for popups that don't
need focus, but still must disappear on their own.
3bcbc8fe8e