I believe it’s a limitation of the webshots software. It ignores the windows setting and uses it’s own. By default, it will stretch the picture but since but only while maintaining the aspect ration. Most webshots are 4:3 ratio which won’t fill up the entire screen. If you uncheck the stretch screen option then it only centers the smaller picture. I suspect it will only work if your pictures are 1280x768 resolution or a multiple of that resolution.