Screen Selection confirmation

[kuroshiropanda]

Is your feature request related to a problem? Please describe.
when it's your first time seeing the screen selection window you wouldn't really know If you selected a screen then applied it, cause you would think closing it would mean cancelling it.

Describe the solution you'd like
An OK button would be nice for confirmation

Describe alternatives you've considered
or double clicking the selected screen would apply and then close the screen selection window