Remove multi-screen handling in DND code
Remove multi-screen handling in DND code

We only have one screen nowadays. No need to carry around
code for handling screen changes.

chergert/gtk,jadahl/gtk,grubersjoe/adwaita,jadahl/gtk,grubersjoe/adwaita,grubersjoe/adwaita,jadahl/gtk,Adamovskiy/gtk,davidgumberg/gtk,davidgumberg/gtk,chergert/gtk,davidgumberg/gtk,chergert/gtk,alexlarsson/gtk,jigpu/gtk,chergert/gtk,chergert/gtk,jadahl/gtk,jigpu/gtk,grubersjoe/adwaita,jigpu/gtk,alexlarsson/gtk,davidgumberg/gtk,Adamovskiy/gtk,davidgumberg/gtk,Adamovskiy/gtk,Adamovskiy/gtk,davidgumberg/gtk,Adamovskiy/gtk,alexlarsson/gtk,davidgumberg/gtk,alexlarsson/gtk,jadahl/gtk,chergert/gtk,grubersjoe/adwaita,alexlarsson/gtk,chergert/gtk,jigpu/gtk,Adamovskiy/gtk,chergert/gtk,grubersjoe/adwaita,jigpu/gtk,grubersjoe/adwaita,grubersjoe/adwaita,jigpu/gtk,jadahl/gtk,Adamovskiy/gtk,Adamovskiy/gtk,alexlarsson/gtk,davidgumberg/gtk,jadahl/gtk,jadahl/gtk,jigpu/gtk,alexlarsson/gtk,alexlarsson/gtk,jigpu/gtk