Add labnag

Based on swaynag (https://github.com/swaywm/sway/tree/master/swaynag)

Copied at commit:
03483ff370

Contains the following modifiations:

- Some functional changes including:
  - Disable exclusive-zone by default (Written-by: @Consolatis) and add
    command line option -x|--exclusive-zone
  - Add close timeout (Written-by: @Consolatis) and -t|--timeout option
  - Use index of button (from right-to-left) for exit code
  - Disable reading from config file and remove associated --type option
- Refactoring including:
  - Use wlr_log() instead of the log.{c,h} functions
  - Use wl_list instead of sway's list.c implementation
  - In the pango wrapper functions, use glib's g_strdup_vprintf() rather
    than the original stringop.c functions
- Align with labwc coding style to pass checkpatch.pl
- Re-licenced from MIT to GPL-2.0, and add Copyright notices for original
  authors

v2

- Remove option -s|--dismiss-button and the default "X" button. To get
  such a button, "-Z X :"
- Remove options -b and -z because there is no requirement to run
  in a terminal.
- Remove *-no-terminal from options --button and --button-dismiss because
  commands are now always run directly without a terminal.

v3

- Allow -B/-Z options without action-argument
- Invert button order of -B/-Z so that `labnag -m foo -Z x -Z y -Z z`
  results in three buttons with "x" furthest to the left, and "z" on the
  right (rather than the other way around).
- Use signalfd() to prevent race conditions on SIGTERM

v4

- Limit number of stdin lines to 200 to avoid hogging CPU

Co-Authored-by: tokyo4j

docs/labnag.1.scd

@@ -0,0 +1,109 @@
+labnag(1)
+
+# NAME
+
+labnag - Show dialog with message and buttons
+
+# SYNOPSIS
+
+_labnag_ [options...]
+
+# OPTIONS
+
+*-B, --button* <text> [<action>]
+	Create a button with the text _text_ that optionally executes _action_
+	when pressed. Multiple buttons can be defined by providing the flag
+	multiple times. Buttons will appear in the order they are provided from
+	lef to right.
+
+*-Z, --button-dismiss* <text> [<action>]
+	Create a button with the text _text_ that optionally executes _action_
+	when pressed, and dismisses labnag. Multiple buttons can be defined by
+	providing the flag multiple times. Buttons will appear in the order
+	they are provided from lef to right.
+
+*-d, --debug*
+	Enable debugging.
+
+*-e, --edge* top|bottom
+	Set the edge to use.
+
+*-y, --layer* overlay|top|bottom|background
+	Set the layer to use.
+
+*-f, --font* <font>
+	Set the font to use.
+
+*-h, --help*
+	Show help message and quit.
+
+*-l, --detailed-message*
+	Read a detailed message from stdin. A button to toggle details will be
+	added. Details are shown in a scrollable multi-line text area.
+
+*-L, --detailed-button* <text>
+	Set the text for the button that toggles details. This has no effect if
+	there is not a detailed message. The default is _Toggle details_.
+
+*-m, --message* <msg>
+	Set the message text.
+
+*-o, --output* <output>
+	Set the output to use. This should be the name of a _xdg\_output_.
+
+*-t, --timeout*
+	Set duration to close dialog. Default is 5 seconds.
+
+*-x, --exclusive-zone*
+	Use exclusive zone. Default is false.
+
+*-v, --version*
+	Show the version number and quit.
+
+# APPEARANCE OPTIONS
+
+*--background* <RRGGBB[AA]>
+	Set the color of the background.
+
+*--border* <RRGGBB[AA]>
+	Set the color of the border.
+
+*--border-bottom* <RRGGBB[AA]>
+	Set the color of the bottom border.
+
+*--button-background* <RRGGBB[AA]>
+	Set the color for the background for buttons.
+
+*--text* <RRGGBB[AA]>
+	Set the text color.
+
+*--button-text* <RRGGBB[AA]>
+	Set the button text color.
+
+*--border-bottom-size* <size>
+	Set the thickness of the bottom border.
+
+*--message-padding* <padding>
+	Set the padding for the message.
+
+*--details-background* <RRGGBB[AA]>
+	Set the color for the background for details.
+
+*--details-border-size* <size>
+	Set the thickness for the details border.
+
+*--button-border-size* <size>
+	Set the thickness for the button border.
+
+*--button-gap* <gap>
+	Set the size of the gap between buttons.
+
+*--button-dismiss-gap* <gap>
+	Set the size of the gap between the dismiss button and another button.
+
+*--button-margin-right* <margin>
+	Set the margin from the right of the dismiss button to edge.
+
+*--button-padding* <padding>
+	Set the padding for the button text.
+

docs/meson.build

@@ -7,6 +7,7 @@ if scdoc.found()
     'labwc-config.5',
     'labwc-menu.5',
     'labwc-theme.5',
+    'labnag.1',
   ]
   foreach manpage : manpages
     markdown = manpage + '.scd'