Mesa 3D, an implementation of several graphics APIs such as Vulkan and OpenGL
Pixman,[11] a low-level software library for pixel manipulation, providing features such as image compositing and trapezoid rasterization; users include the cairo graphics library and the X.Org Server
libinput,[13] a library to handle input devices in Wayland compositors and to provide a generic X.Org input driver. It provides device detection, device handling, input device event processing and abstraction to minimize the amount of custom input code compositors need to provide the common set of functionality that users expect.
PulseAudio, a sound server frontend providing software mixing, network audio, and per application volume control
XDG Base Directory Specification (XDG BDS) introduces a range of variables where user-specific files used by programs should be found.[14] Many tools and applications utilize these variables by default.[15]
User directories
Besides the variables mentioned below, XDG BDS also specifies that users' local binary files may be installed into $HOME/.local/bin. Systems compliant with the spec are expected to make this directory available in their CLI's PATH environment variable.[14]
XDG_DATA_HOME
For user application's own data files
Default to $HOME/.local/share
XDG_CONFIG_HOME
For user's app configuration files
Default to $HOME/.config
XDG_STATE_HOME
For user-specific app session data, which should be stored for future reuse
Default to $HOME/.local/state
May include logs, recently used files, application-specific information (e.g. window layout, views, opened files, undo history, etc.), akin to session data that should be stored by app by request of system session manager, like X session manager
XDG_CACHE_HOME
For user-specific apps cache files
Default to $HOME/.cache
XDG_RUNTIME_DIR
For user-specific app runtime files like sockets which must not survive reboot and full logout/login cycles
System directories
XDG_DATA_DIRS
Colon-separated list of preference-ordered paths to search for data files in
Default to /usr/local/share/:/usr/share/
XDG_CONFIG_DIRS
The same as above but for config files
Default to /etc/xdg/
Stated aims
The project aims to catch interoperability issues much earlier in the process. It is not for legislating formal standards. Stated goals include:
Collect existing specifications, standards, and documents related to X desktop interoperability and make them available in a central location.
Promote the development of new specifications and standards to be shared among multiple X desktops.
Integrate desktop-specific standards into broader standards efforts, such as Linux Standard Base and the ICCCM.
Work on the implementation of these standards in specific X desktops.
Serve as a neutral forum for sharing ideas about X desktop technology.
Implement technologies that further X desktop interoperability and free X desktops in general.
Promote X desktops and X desktop standards to application authors, both commercial and volunteer.
Communicate with the developers of free operating system kernels, the X Window System itself, free OS distributions, and so on to address desktop-related problems.
Provide source repositories (git[16] and CVS[17]), web hosting, Bugzilla, mailing lists, and other resources to free software projects that work toward the above goals.