The display server is the software that renders graphic requests on the part of applications. Initially, we plan to use the X window system display server, because it works well and is widely used.
There are some problems with the X window system, though, that might make us want to have our own display server at some point:
There is a project by Alastair Bridgewater to write an X server in Common Lisp, and this might be a good start for a display server for Gracle. Certainly, it would be a great advantage if the new display server were compatible with the X server so that it can become a drop-in replacement for existing X servers. Additional features could then be added through the use of the X protocol extension mechanism as usual.
There are rumors that some organization is planning a major overhaul to their existing X server, and that instead of using vendor-specific drivers for accessing graphics hardware, it will use OpenGL exclusively. This would greatly simplify the code, and we might consider doing something similar, so as not to have to write lots and lots of drivers. I don't know how good OpenGL is for this kind of use, though.