http://askubuntu.com/a/11877/19466 http://askubuntu.com/a/11877/19466 : X has two drawing APIs. One of these is a part of the core X11 protocol, which is ancie

http://askubuntu.com/a/11877/19466 http://askubuntu.com/a/11877/19466 : X has two drawing APIs. One of these is a part of the core X11 protocol, which is ancient, useless, and nobody uses. The other is the XRender extension which provides modern composite operations, among other things such as gradients. This is what Cairo, for example, uses. X also has font drawing APIs. http://julien.danjou.info/blog/2010/thoughts-and-rambling-on-the-X-protocol http://julien.danjou.info/blog/2010/thoughts-and-rambling-on... : The X11 protocol (without extensions) defines about 120 types of requests: create a window, move a window, etc. Nowadays, there's at least 25 % of them which are useless: usage of server-side font, or the drawing of squares and polygon, are unused by any modern application or toolkit. All of this is superseded by requests from extensions, like the XRender one. The handling of multiple monitors displays has totally been screwed up. X11 has been designed to work in Zaphod mode (independent monitors). But Xinerama, and nowadays XRandR have replaced it up: recent X servers (released after ~2007) does not support Zaphod mode anymore, even if it's a core piece of the X11 protocol.