xwayland: support xinitrc scripts to configure server on launch (#1963)

docs/README

@@ -5,6 +5,7 @@ Config layout for ~/.config/labwc/
 - rc.xml
 - shutdown
 - themerc-override
+- xinitrc
 
 See `man labwc-config and `man labwc-theme` for further details.
 

docs/labwc-config.5.scd

@@ -8,7 +8,7 @@ labwc - configuration files
 
 Labwc uses openbox-3.6 specification for configuration and theming, but does not
 support all options. The following files form the basis of the labwc
-configuration: rc.xml, menu.xml, autostart, shutdown and environment.
+configuration: rc.xml, menu.xml, autostart, shutdown, environment and xinitrc.
 
 No configuration files are needed to start and run labwc.
 
@@ -78,6 +78,10 @@ in labwc-theme(5).
 *rc.xml* is the main configuration file and all its options are described in
 detail below.
 
+The *xinitrc* file is executed as a shell script whenever labwc launches the
+Xwayland X11 server. This may happen multiple times throughout the session if
+Xwayland is not configured to persist when no X11 clients are connected.
+
 # CONFIGURATION
 
 This section describes *rc.xml* configuration options.

docs/xinitrc

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+## This file is run every time labwc launches Xwayland.
+##
+## In the default configuration, Xwayland will be launched lazily, and will
+## terminate after several seconds when no X11 clients are connected. Thus,
+## this script may run repeatedly throughout a single labwc session.
+
+# Configure the X resource database if a file is provided
+#
+# NOTE: when Xwayland is launched lazily, an X11 client that triggers its
+# launch may attempt to read the resource database before this command can be
+# run. In that case, it is recommended to make a symlink to .Xdefaults:
+#
+#     ln -s .Xresources "${HOME}/.Xdefaults"
+#
+# With this link in place, X11 applications will fall back to reading
+# the .Xdefaults file directly when no resource database can be read from the
+# server's root window properties.
+#
+# Invoking xrdb is still useful to pre-load the resource database for
+# subsequent clients, because any additional clients launched while the X
+# server remains alive will be able to query the database without resorting to
+# filesystem access.
+
+if [ -r "${HOME}/.Xresources" ] && command -v xrdb >/dev/null 2>&1; then
+	xrdb -merge "${HOME}/.Xresources"
+fi