[bug] Black window of 2nd screen moves to the 1st screen instead of disposing

[TuTAH1]

To reproduce:

1. Launch Black Screens
2. Enable black screen on 2nd monitor
3. Turn off second monitor

Expected behaviour

black screen "stays" on second monitor or dispose

Current behavour

Black screen moves to the 1st monitor, without possibility to turn it off

Additional notes

I think the solution is the same as #7 with a little additions.