@nzjrs I have looked into gtkglext for Gtk3 and there has been no activity on the github repository for the last year. However as Gtk3 uses cairo, some of the underlying rendering engines (such as XRender) support hardware acceleration when the drivers are available (NVIDEA/Intel provide XLib drivers for their hardware). OpenGL support on cairo is provided by cairo-gl, and cairo-glx which are part of cairo. In the meantime, I have disabled OpenGL support when building for Gtk3 as this includes obsolete Gtk2 code and breaks the build.