Internal Program Version: libxcb  1.15

The X protocol C-language Binding (XCB) is a replacement for Xlib
featuring a small footprint, latency hiding, direct access to the
protocol, improved threading support, and extensibility.

The X Window System provides support for changing the image on a
display screen after a user-settable period of inactivity to avoid
burning the cathode ray tube phosphors. This extension allows an
external "screen saver" client to detect when the alternate image is
to be displayed and to provide the graphics.

http://xcb.freedesktop.org