Libxfce4ui spawn api break

[Nick Schermer]

People,

While i was adding startup notification support to the thunar uca
plugin, i discovered some applications might need to have the pid of
the spawned process [to setup a g_child_watch_add(_full)] to monitor
when it exits (in case of the uca plugin: it refreshed the working
directory of the action to make sure file changes are visible, even on
volumes that don't support file monitoring or when file monitoring is
somehow disabled).

So I'd like to add a pid return field like this:

gboolean
xfce_spawn_on_screen (GdkScreen    *screen,
                      const gchar  *working_directory,
                      gchar       **argv,
                      gchar       **envp,
                      GSpawnFlags   flags,
                      gboolean      startup_notify,
                      guint32       startup_timestamp,
                      const gchar  *icon_name,
                      GPid         *child_pid, /* <-- new variable */
                      GError      **error);

The xfce_spawn_command_line_on_screen() function won't be touched.

Any objections, better ideas?

Nick