qt: fix CompositorDCompositionAcrylicSurface causing the interface window to be inactive

CompositorDCompositionAcrylicSurface creates a window itself, which makes the newly shown interface window to be no longer active.

The interface window is just shown, it should be active. At the same time, the window CompositorDCompositionAcrylicSurface creates is a dummy window, so it does not make sense for it to request (and steal from the interface window) activation.

Request review @chub.