isComposited
Returns whether surfaces can reasonably be expected to have their alpha channel drawn correctly on the screen.
Check method@Gdk.Display.is_rgba for whether the display supports an alpha channel.
On X11 this function returns whether a compositing manager is compositing on @display.
On modern displays, this value is always true.
Return
Whether surfaces with RGBA visuals can reasonably be expected to have their alpha channels drawn correctly on the screen.