[MutterWindow] Added meta_window_get_transient_for_as_xid()

Accessor for the transient xid hint.

https://bugzilla.gnome.org/show_bug.cgi?id=597010

src/core/window.c

@@ -8860,6 +8860,25 @@ meta_window_get_transient_for (MetaWindow *window)
     return NULL;
 }
 
+/**
+ * meta_window_get_transient_for_as_xid:
+ * @window: a #MetaWindow
+ *
+ * Returns the XID of the window that is pointed to by the
+ * WM_TRANSIENT_FOR hint on this window (see XGetTransientForHint()
+ * or XSetTransientForHint()). Metacity keeps transient windows above their
+ * parents. A typical usage of this hint is for a dialog that wants to stay
+ * above its associated window.
+ *
+ * Return value: (transfer none): the window this window is transient for, or
+ * None if the WM_TRANSIENT_FOR hint is unset.
+ */
+Window
+meta_window_get_transient_for_as_xid (MetaWindow *window)
+{
+  return window->xtransient_for;
+}
+
 /**
  * meta_window_get_pid:
  * @window: a #MetaWindow

src/include/window.h

@@ -116,6 +116,7 @@ void        meta_window_minimize           (MetaWindow  *window);
 void        meta_window_unminimize         (MetaWindow  *window);
 const char *meta_window_get_title (MetaWindow *window);
 MetaWindow *meta_window_get_transient_for (MetaWindow *window);
+Window      meta_window_get_transient_for_as_xid (MetaWindow *window);
 void        meta_window_delete             (MetaWindow  *window,
                                             guint32      timestamp);
 guint       meta_window_get_stable_sequence (MetaWindow *window);