Current behaviour: can still interact with the screen behind the effect.

For me, I'd like to exchange this functionality for faster closing of the window via a System Settings toggle.

To show this setting state, the background could be dimmed and/or blurred the way it is when other menus that function this way are up, like the clear all clips popup.

In particular, I would like this feature because the X in the top left is very hard to hit quickly and can result in an accidental press of the fullscreen button or no result at all.