Add option to pause on fullscreen

[tonehrk]

I like to have my taskbar with transparent and blur effect, while the animated wallpaper is visible beneath the taskbar (which is not possible with the 'on maximized window' option). But I would like it to pause when running games or watching movies in fullscreen mode, since the wallpaper wouldn't be visible on the screen anyway, and I think it could also help with performance on less powerful computers.

Regards!