fix deprecation warning: try the new recommended way first, fallback …

…to the old one

git-svn-id: https://xpra.org/svn/Xpra/trunk@17579 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/client/notifications/dbus_notifier.py

@@ -5,9 +5,14 @@
 
 import os
 from xpra.client.notifications.notifier_base import NotifierBase, log
-#beware: this import has side-effects:
-import dbus.glib
-assert dbus.glib
+try:
+    #new recommended way of using the glib main loop:
+    from dbus.mainloop.glib import DBusGMainLoop
+    DBusGMainLoop(set_as_default=True)
+except:
+    #beware: this import has side-effects:
+    import dbus.glib
+    assert dbus.glib
 import dbus.exceptions
 
 NOTIFICATION_APP_NAME = os.environ.get("XPRA_NOTIFICATION_APP_NAME", "%s (via Xpra)")