Make it possible to select area of the window to use as PiP

[TicTac7x]

Something that i have been looking for ages, pretty much have the PiP functionality as in elementary OS. Win + T and then start selecting the area of the window you want to use for the thumbnail. Super useful to have a really small portion of a game as the thumbnail. For example, one could use it to PiP your health of a game.