AcceleratedBackingStoreWayland uses gdk_cairo_draw_from_gl, which is documented as "The main way to not draw GL content in GTK." """ The function is overly complex and produces broken output in various combinations of arguments. If you want to draw with GL textures in GTK, use gdk_gl_texture_new(); if you want to use that texture in Cairo, use gdk_texture_download() to download the data into a Cairo image surface. """ I noticed due to some discussion at Red Hat about how it's currently broken. See https://gitlab.gnome.org/GNOME/gtk/-/issues/5517 where it's not flushing properly. No clue whether it would be feasible to avoid it or not. I've never attempted to understand graphics.