dwl - dwm for Wayland

dwl is a compact, hackable compositor for Wayland based on wlroots. It is intended to fill the same space in the Wayland world that dwm does in X11, primarily in terms of philosophy, and secondarily in terms of functionality. Like dwm, dwl is:

• Easy to understand, hack on, and extend with patches
• One C source file (or a very small number) configurable via config.h
• Limited to a maximum number of SLOC (to be determined)
• Tied to as few external dependencies as possible

dwl is not meant to provide every feature under the sun. Instead, like dwm, it sticks to features which are necessary, simple, and straightforward to implement given the base on which it is built. Since wlroots provides a number of features that are more complicated to accomplish with Xlib and select extensions, dwl can be in some ways more featureful than dwm while remaining just as simple. Intended default features are:

• Any features provided by dwm/Xlib: simple window borders, tags, keybindings, client rules, mouse move/resize (see below for why the built-in status bar is a possible exception)
• Configurable multi-monitor layout support, including position and rotation
• Configurable HiDPI/multi-DPI support
• Wayland protocols needed for daily life in the tiling world: at a minimum, xdg-shell and layer-shell (for bars/menus). Protocols trivially provided by wlroots may also be added.
• XWayland support as provided by wlroots
• Zero flickering - Wayland users naturally expect that "every frame is perfect"
• Basic yes/no damage tracking to avoid needless redraws (if it can be done simply and has an impact on power consumption)

Other features under consideration are:

• Additional Wayland compositor protocols which are trivially provided by wlroots or can be conditionally included via config.h settings (e.g. screen capture)
• External bar support instead of a built-in status bar, to avoid taking a dependency on FreeType or Pango
• Buffering of input when spawning a client so you don't have to wait for the window (use wl_client_get_credentials to get the PID) - would this require passing through something like dmenu? Extension protocol?
• More in-depth damage region tracking

Feature non-goals include:

• Client-side decoration (any more than is necessary to tell the clients not to)
• Client-initiated window management, such as move, resize, and close, which can be done through the compositor

Building dwl

dwl has only two dependencies: wlroots (git version currently required) and wayland-protocols. Simply install these and run make.

Configuration

All configuration is done by editing config.h and recompiling, in the same manner as dwm. There is no way to separately restart the window manager in Wayland without restarting the entire display server, so any changes will take effect the next time dwl is executed.

Running dwl

dwl can be run as-is, with no arguments. In an existing Wayland or X11 session, this will open a window to act as a virtual display. When run from a TTY, the Wayland server will take over the entire virtual terminal. Clients started by dwl will have WAYLAND_DISPLAY set in their environment, and other clients can be started from outside the session by setting this variable accordingly.

You can also specify a startup program using the -s option. The argument to this option will be run at startup as a shell command (using sh -c) and can serve a similar function to .xinitrc: starting a service manager or other startup applications. Unlike .xinitrc, the display server will not shut down when this process terminates. Instead, as dwl is shutting down, it will send this process a SIGTERM and wait for it to terminate (if it hasn't already). This makes it ideal not only for initialization but also for execing into a user-level service manager like s6 or systemd --user.

Note: Wayland requires a valid XDG_RUNTIME_DIR, which is usually set up by a session manager such as elogind or systemd-logind. If your system doesn't do this automatically, you will need to configure it prior to launching dwl, e.g.:

export XDG_RUNTIME_DIR=/tmp/xdg-runtime-$(id -u)
mkdir -p $XDG_RUNTIME_DIR

Known limitations and issues

dwl is a work in progress, and it has not yet reached its feature goals in a number of ways:

• A window's texture is scaled for its "home" monitor only (noticeable when window sits across a monitor boundary)
• XWayland support is new and could use testing
• Urgent/attention/focus-request (not yet supported by xdg-shell protocol)
• Statusbar support (built-in or external)
• layer-shell
• Damage tracking
• Fullscreen/fixed windows (or whatever the Wayland analogues are)

Acknowledgements

dwl began by extending the TinyWL example provided (CC0) by the sway/wlroots developers. This was made possible in many cases by looking at how sway accomplished something, then trying to do the same in as suckless a way as possible. Speaking of which, many thanks to suckless.org and the dwm developers and community for the inspiration.