xfrun + dbus integration

[Nick Schermer]

I've got an other warning when running xfrun4 twice (or more) (daemon
already running in terminal) and then close both dialogs:

(xfrun4:18063): GLib-GObject-WARNING **: invalid uninstantiatable type
`<invalid>' in cast to `GtkWindow'
(xfrun4:18063): GLib-GObject-WARNING **: instance of invalid
non-instantiatable type `<invalid>'
(xfrun4:18063): GLib-GObject-CRITICAL **: g_signal_emit_valist:
assertion `G_TYPE_CHECK_INSTANCE (instance)' failed

Greets,
Nick