Set if the backend supports offscreen rendering.
Set if the backend supports GLSL shaders.
Set if stage has a graphical cursor.
Set if multiple stages are supported.
Set if stage size if fixed (i.e framebuffer)
Set if stage is able to be user resized.
Set if the GLX_INTEL_swap_event is supported.
Set if vblank syncing supported.
Set if NPOTS textures supported.
Set if texture pixels can be read.
Set if YUV based textures supported.
Runtime flags indicating specific features available via Clutter window system and graphics backend.