Created attachment 290625 [details] Screenshot showing the problem Attached screenshot shows the issue. I managed to reproduce it with 2.14.0 and not with 2.12, so did mcatanzaro. One of the builds I tried was from before using gdk_cairo_draw_from_gl, and I can also reproduce when using the Apertis clutter wrapper rendering path, so it is likely coming from the web process that way. I suppose it might be related to the threaded compositor.