Check for grip_window != NULL in gtk_window_draw
Check for grip_window != NULL in gtk_window_draw

This is safer, since GtkWindow subclasses may override realize
and end up with has_resize_grip == TRUE, but grip_window still
being NULL - as is the case with GtkPlug.

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