.Dd June 11, 2023
.Dt DISPLAY 1
.Os
.Sh NAME
.Nm display
.Nd desktop environment
.Sh SYNOPSIS
.Nm
.Op Ar session ...
.Sh DESCRIPTION
.Nm
is a desktop environment and windowing system compositor.
Applications talk to the
.Nm
server process to receive user input and show their graphical user interfaces
in windows.
.Pp
The user's preferred startup applications are launched on startup by launching
the
.Xr session 5
program (if set) or otherwise the
.Xr displayrc 5
script in the background.
.Pp
.Nm
exits when Control + Alt + Delete is pressed.
.Pp
The options are as follows:
.Bl -tag -width "12345678"
.It Fl m Ar mouse
Use
.Pa mouse
device instead of
.Pa /dev/mouse .
.It Fl t Ar tty
Use
.Pa tty
device instead of
.Pa /dev/tty .
.It Fl s Ar socket
Listen on
.Pa socket
instead of
.Pa /var/run/display .
.El
.Pp
The keyboard shortcuts are as follows:
.Bl -tag -width "Control + Alt + Delete"
.It Alt + F4
Quit the current window.
.It Alt + F10
Maximize (or restore) the current window.
.It Alt + Tab
Switch to the next window.
.It Alt + Drag
Drag the current window.
.It Control + Alt + Delete
Exit the desktop environment.
.It Control + Alt + T
Launch the
.Xr terminal 1
application.
.It Super + Left
Tile the current window leftwards.
.It Super + Right
Tile the current window rightwards.
.It Super + Up
Tile the current window upwards.
.It Super + Down
Tile the current window downwards.
.It F11
Grab input for the current window.
.It F12
Release the input grab on the current window.
.El
.Pp
The mouse gestures are as follow:
.Bl -bullet
.It
Clicking on a window brings it to the foreground.
.It
Dragging the window title bar moves the window.
.It
Double clicking on the window title bar maximizes (or restores) the window.
.It
Clicking on the rectangle icon in the title bar maximizes (or restores) the
window.
.It
Clicking on the X icon in the title bar closes the window.
.It
Dragging the edges of a window resizes it.
.It
Windows can be tiled by moving them when the cursor meets the left, right, top,
and bottom edges or any corner.
.El
.Pp
The keyboard layout can be changed with the
.Xr chkblayout 1
program.
The display resolution can be changed with the
.Xr chvideomode 1
program.
.Sh ENVIRONMENT
.Bl -tag -width "DISPLAY_SOCKET"
.It Ev DISPLAY_SOCKET
.Nm
sets
.Ev DISPLAY_SOCKET
to the path of the
.Xr unix 4
socket where it listens for connections from applications.
Applications use
.Ev DISPLAY_SOCKET
to connect to
.Nm
or
.Pa /var/run/display
by default.
.El
.Sh FILES
.Bl -tag -width 12345678 -compact
.It Pa ~/.displayrc , /etc/displayrc , /etc/default/displayrc
.Xr displayrc 5
script that spawns the user's preferred startup applications.
.It Pa /var/run/display
.Xr unix 4
socket where
.Nm
listens for connections from applications, as advertised in the
.Ev DISPLAY_SOCKET
environment variable.
.El
.Sh ASYNCHRONOUS EVENTS
.Bl -tag -width "SIGTERM"
.It Dv SIGTERM
Request daemon termination.
.El
.Sh EXIT STATUS
.Nm
runs as a
.Xr daemon 7
until stopped by
.Dv SIGTERM ,
the user explicitly exits the desktop environment, or an application asks
it to exit.
.Nm
signals readiness on the
.Ev READYFD
file descriptor when the display server is ready to receive connections from
applications.
.Nm
will exit non-zero on any fatal startup error.
.Sh EXAMPLES
.Nm
can be selected as the user's graphical user interface with this executable
.Pa ~/.session
script:
.Bd -literal -offset indent
#!/bin/sh
exec display
.Ed
.Pp
.Xr chkblayout 1 ,
.Xr chvideomode 1 ,
.Xr display 1
will run the
.Xr displayrc 5
script on startup, which can be used to start applications.
.Sh SEE ALSO
.Xr terminal 1 ,
.Xr displayrc 5 ,
.Xr session 5
.Sh BUGS
The following features are not yet implemented:
.Bl -bullet -compact
.It
Windows cannot be minimized.
.It
Applications cannot receive mouse events.
.It
The wallpaper is random and cannot be controlled.
.El