As an UWP App runs in window mode on common desktop systems the \"old\" way of getting the screen resolution won\'t work anymore.
Old Resolution with Window.C
Okay so the Answer from Juan Pablo Garcia Coello lead me to the Solution - Thanks for that!
You can use
var bounds = ApplicationView.GetForCurrentView().VisibleBounds;
but you must call it before the windows is displayed in my case right after
Window.Current.Activate();
is a good place. At this time you will get the bounds of the window on which your app will appear.
Thanks a lot for help me solving it :)
Regards Alex