Generic sikuli logic if screen postion got changed

I guess you are working with absolute Regions ( Region(x, y, w, h) ).

If your search area (in your case the window) might change position and/or size between scrip runs, you have to some how get the window are either based on the App class (see docs) or by searching a fixed key visual (logo, header, ...) from where you calculate the search area, e.g.

ref = find(key_visual)
window = Region(ref.x-50, ref.y-20, 600, 400)

more options like Region.left(), ... can be found in the docs.

If you follow RaiMans suggestion to search for one or more visual key elements from which you can determine the position of the window, you can pack this functionality into an observer and run it in the background so that it observes the logo/header of the window and recalculates the right window position everytime its location changes.

I would not recommend the App class because it often did not work as expected in my scripts.

If performance is not critical for you, you could also change the Region where you search your text to SCREEN, so the whole screen will be searched for the text, but this is a rather bad solution ;-)

Thanks for your reply.