Add a method to GSDisplayServer that allows you to obtain the

identifier used by the backend's windowing system instead of
just the GNUstep-internal window number. On X11, the identifier
is useful, among other things, to implement the D-Bus menu 
protocol.


git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/back/trunk@37533 72102866-910b-0410-8b05-ffd578937521

ChangeLog

@@ -1,3 +1,7 @@
+2014-01-01 Niels Grewe <niels.grewe@halbordnung.de>
+        * Source/x11/XGServerWindow.m: Implement method to get
+	the XWindow ID of the a window from its window number.
+
 2013-12-29  Fred Kiefer <FredKiefer@gmx.de>
 
 	* Source/cairo/CairoGState.m (-GSSetFont:),

Source/x11/XGServerWindow.m

@@ -2291,6 +2291,17 @@ _get_next_prop_new_event(Display *display, XEvent *event, char *arg)
   return window->number;
 }
 
+- (void*)backendIdentifierForWindow: (int)win
+{
+  gswindow_device_t *window;
+  window = WINDOW_WITH_TAG(win);
+  if (!window)
+    {
+      return NULL;
+    }   
+  return (void*)(intptr_t)window->ident;
+}
+
 - (void) termwindow: (int)win
 {
   gswindow_device_t *window;