And again one more question concerning windows:
When we have two fullscreen windows of different screen resolution, and we want to switch between them using SetActive() and Show(), we have the problem that the DisplaySettings not correspond, but for both windows the DisplaySettings of the last created window are applied.
What is needed is an additional change of the Display Settings.
At least in MS-Windows it can be done with: "ChangeDisplaySettings()"
SFML does not provide anything, to do that with a function call, other than when creating a window, right?