Add screensaver inhibition control service

The service enables or disables swayidle inhibition depending on
whether any audio plays or not. It replaces the activation of
inhibition for fullscreen browser windows.

etc/sway/config.d/30-applications-defaults.conf

@@ -45,21 +45,6 @@ for_window [title="Confirm to replace files"] move position center
 for_window [title="Choose an Application"] floating enable
 for_window [title="Removable medium is inserted"] floating enable
 
-# apply mark for Xwayland and wayland native browser windows
-for_window [class="Chromium-browser"] mark Browser
-for_window [class="Brave-browser"] mark Browser
-for_window [class="firefox"]  mark Browser
-for_window [class="librewolf"] mark Browser
-for_window [app_id="Chromium-browser"] mark Browser
-for_window [app_id="brave-browser"] mark Browser
-for_window [app_id="[Ff]irefox"] mark Browser
-for_window [app_id="[Ll]ibrewolf"] mark Browser
-
-# inhibit scrensaver for fullscreen browser windows
-for_window [con_mark="Browser"] {
-    inhibit_idle fullscreen
-}
-
 # Don't allow applications to inhibit shortcuts, i.e. grab total control of the
 # keyboard. Chrome currently abuses this by enabling it for all "--app=..."
 # shortcuts.

usr/lib/systemd/user/swayidle-inhibitor.service

@@ -0,0 +1,12 @@
+[Unit]
+Description=Toggle idle inhibition depending on whether the audio is playing or not
+PartOf=swayidle.service
+After=swayidle.service
+
+[Service]
+ExecStart=/usr/share/sway/scripts/idle-inhibitor.sh
+Restart=always
+RestartSec=30
+
+[Install]
+WantedBy=sway-session.target

usr/share/sway/scripts/idle-inhibitor.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+set -e
+
+if grep -s -l -v "closed" /proc/asound/card*/pcm*/sub*/status; then
+  swaymsg inhibit_idle open
+  printf "Idle inhibition is ON."
+else
+  swaymsg inhibit_idle none
+  printf "Idle inhibition is OFF."
+fi