gdk: offscreen window source drawable now is the root window
gdk: offscreen window source drawable now is the root window

As the source drawable is only used for creating pixmaps these days, we
don't have to keep a real drawable around, but can just use the root
window.

bratsche/gtk-,Distrotech/gtk2,grubersjoe/adwaita,Lyude/gtk-,Adamovskiy/gtk,grubersjoe/adwaita,davidt/gtk,alexlarsson/gtk,davidgumberg/gtk,Distrotech/gtk2,grubersjoe/adwaita,jadahl/gtk,davidgumberg/gtk,davidgumberg/gtk,chergert/gtk,Sidnioulz/SandboxGtk,Sidnioulz/SandboxGtk,Lyude/gtk-,ahodesuka/gtk,grubersjoe/adwaita,davidgumberg/gtk,bratsche/gtk-,jessevdk/gtk,jadahl/gtk,jigpu/gtk,jessevdk/gtk,davidt/gtk,jigpu/gtk,simokivimaki/gtk,alexlarsson/gtk,Distrotech/gtk2,davidgumberg/gtk,Adamovskiy/gtk,davidt/gtk,Adamovskiy/gtk,jigpu/gtk,alexlarsson/gtk,ahodesuka/gtk,Lyude/gtk-,alexlarsson/gtk,jigpu/gtk,simokivimaki/gtk,ebassi/gtk,grubersjoe/adwaita,ebassi/gtk,Adamovskiy/gtk,Lyude/gtk-,chergert/gtk,jadahl/gtk,ahodesuka/gtk,bratsche/gtk-,Lyude/gtk-,chergert/gtk,ebassi/gtk,Sidnioulz/SandboxGtk,chergert/gtk,grubersjoe/adwaita,jigpu/gtk,jigpu/gtk,msteinert/gtk,jadahl/gtk,Sidnioulz/SandboxGtk,Adamovskiy/gtk,bratsche/gtk-,Sidnioulz/SandboxGtk,ebassi/gtk,ahodesuka/gtk,ebassi/gtk,msteinert/gtk,davidgumberg/gtk,bratsche/gtk-,chergert/gtk,msteinert/gtk,alexlarsson/gtk,jigpu/gtk,bratsche/gtk-,davidgumberg/gtk,davidgumberg/gtk,simokivimaki/gtk,Distrotech/gtk2,davidt/gtk,simokivimaki/gtk,alexlarsson/gtk,ahodesuka/gtk,jigpu/gtk,chergert/gtk,Distrotech/gtk2,jessevdk/gtk,chergert/gtk,jadahl/gtk,alexlarsson/gtk,jadahl/gtk,Adamovskiy/gtk,ahodesuka/gtk,ahodesuka/gtk,jessevdk/gtk,davidt/gtk,alexlarsson/gtk,Lyude/gtk-,grubersjoe/adwaita,jadahl/gtk,Lyude/gtk-,simokivimaki/gtk,Adamovskiy/gtk,Lyude/gtk-,jessevdk/gtk,msteinert/gtk,Distrotech/gtk2,simokivimaki/gtk,jessevdk/gtk,Sidnioulz/SandboxGtk,msteinert/gtk,grubersjoe/adwaita,davidt/gtk,ebassi/gtk,msteinert/gtk,jadahl/gtk,chergert/gtk,Adamovskiy/gtk,jessevdk/gtk,ahodesuka/gtk