Improvement: ARGB window matching & Enable track_focus with D-Bus

- Add predefined matching target "argb" to match ARGB windows.

- Make it possible to enable focus tracking on-the-fly with D-Bus
  method.

dbus-examples/cdbus-driver.sh

@@ -25,6 +25,9 @@ type_enum='uint16'
 # List all window ID compton manages (except destroyed ones)
 dbus-send --print-reply --dest="$service" "$object" "${interface}.list_win"
 
+# Ensure we are tracking focus
+dbus-send --print-reply --dest="$service" "$object" "${interface}.opts_set" string:track_focus boolean:true
+
 # Get window ID of currently focused window
 focused=$(dbus-send --print-reply --dest="$service" "$object" "${interface}.find_win" string:focused | $SED -n 's/^[[:space:]]*'${type_win}'[[:space:]]*\([[:digit:]]*\).*/\1/p')