Window.markPaintFromClip

If you call this during a paint (e.g. between [gdk.window.Window.beginPaintRegion] and [gdk.window.Window.endPaint] then GDK will mark the current clip region of the window as being drawn. This is required when mixing GL rendering via [gdk.global.cairoDrawFromGl] and cairo rendering, as otherwise GDK has no way of knowing when something paints over the GL-drawn regions.

This is typically called automatically by GTK+ and you don't need to care about this.