Thanks Shawn. Excellent explainer. I have tried everything. In every different sequence I can imagine. I have had this problem with every computer I have owned since Windows 10, and with multiple configurations. Strange that it has happened on every single one. Or from my perspective strange that anybody doesn't have this problem.

There are several ways here and from other forums where I can make the shadows go away. The only trouble is they will always come back when using Win+Tab or snapping windows to the edge.

I am left wondering, if there are people out there who don't have this problem, is it possible there might be something I haven't tried. Your post Shawn seems to be the most comprehensive I have seen.