Ideal OS: Rebooting the Desktop Operating System Experience

Now we can add in a compositing window manager that really just moves surfaces around in 3D, transforms coordinates, and is controlled through messages. Most of what a typical window manager does, like arranging windows, overlaying notifications, and determining which window has focus; can actually be done by other programs who just send messages to the compositor to do the real work.

This means the compositor is heavily integrated with the graphics driver, which is essential to making such a system fast. Below is the diagram for Wayland, the compositor which will eventually become the default for desktop Linux.

Applications would do their drawing by requesting a graphics surface from the compositor. When they finish their drawing and are ready to update they just send a message saying: please repaint me. In practice we'd probably have a few types of surfaces for 2d and 3d graphics, and possibly raw framebuffers. The important thing is that at the end of the day it is the compositor which controls what ends up on the real screen, and when. If one app goes crazy the compositor can throttle it's repaints to ensure the rest of the system stays live.