LibXext provides an X Window System client interface to several extensions to
the X protocol.
The supported protocol extensions are:
- DOUBLE-BUFFER (DBE), the Double Buffer extension;
- DPMS, the VESA Display Power Management System extension;
- Extended-Visual-Information (EVI), an extension for gathering extra
information about the X server's visuals;
- LBX, the Low Bandwidth X extension;
- MIT-SHM, the MIT X client/server shared memory extension;
- MIT-SUNDRY-NONSTANDARD, a miscellaneous extension by MIT;
- Multi-Buffering, the multi-buffering and stereo display extension;
- SECURITY, the X security extension;
- SHAPE, the non-rectangular shaped window extension;
- SYNC, the X synchronization extension;
- TOG-CUP, the Open Group's Colormap Utilization extension;
- XC-APPGROUP, the X Consortium's Application Group extension;
- XC-MISC, the X Consortium's resource ID querying extension;
- XTEST, the X test extension (this is one of two client-side implementations;
the other is in the libXtst library, provided by the libxtst6 package);

LibXext also provides a small set of utility functions to aid authors of client
APIs for X protocol extensions.