Instead, use a pipe. Check if the pipe is readable in the steamcompmgr event loop. This avoids a roundtrip through the X11 server. Closes: https://github.com/Plagman/gamescope/issues/201
For now just mark one repaint per refresh interval without any particular alignment, as that can be hard to get in nested. We'll use the display timing extensions for that later. We'll have it align properly in embedded mode soon.