Fix background clearing when exposing with non-double buffered widgets
Fix background clearing when exposing with non-double buffered widgets

We used to set a flushed boolean whenever we flushing double buffered
areas to the window due to a non-db draw. We then read back from the
window if this was set. This broke when we were doing multiple paints
of the same area after a flush as we were re-reading the window each
time, overdrawing what was previously draw.

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