I'm running Classic Shell Version 4.3.0 and my OS is Windows 10. I'm using a 4k monitor (3840x2160), but play games in 1920x1080, or 2560x1440. I don't think res is affecting this bug.
If I replace my windows 10 start button (with the default shell image or a custom one), the button is clickable in full screen games and apps. Here is a picture of what I mean. I had to use my phone to take this picture, as print screen wouldn't work.
http://i.imgur.com/gQpUxuo.jpgIn the bottom left, you can clearly see the mouse. If you happen to click, it will minimize the application. (It is very annoying!)
if I print screen you can see this
http://i.imgur.com/pDaLjnF.jpgIf I choose not to replace the start button and just use the default windows 10 button, the bug is solved. No more cursor on the bottom left of the screen.
Print screen appears like this
http://i.imgur.com/pPkJm5F.jpgIs there any way to solve this issue with a custom button?