libXext is the historical libX11-based catchall library for the X11 extensions without their own libraries. libXext provides functions for: Double Buffer Extension (DBE), Display Power Management Signaling (DPMS), X11 Nonrectangular Window Shape Extension (XShape), shared memory extensions (XShm), TOG-CUP (Xcup), X11 Extended Visual Information extension (EVI), X11 Double-Buffering, Multi-Buffering, and Stereo Extension (Xmbuf).