--- ./src/xfdesktop-window-icon-manager.c
+++ ./src/xfdesktop-window-icon-manager.c
@@ -600,7 +600,14 @@
         g_object_weak_ref(G_OBJECT(window), window_destroyed_cb, wmanager);
     }
     
-    workspace_changed_cb(wmanager->priv->wnck_screen, NULL, wmanager);
+    /* as of libwnck 2.20, the "active-workspace-changed" signal has
+     * a new prototype with an extra argument.  previous versions don't
+     * have this argument, so we fudge this here (bug 4395). */
+    /* we must of course also emulate this behaviour here (stupid bug). */
+    if(G_LIKELY(__wnck_has_new_active_workspace_changed_signal))
+        workspace_changed_cb(wmanager->priv->wnck_screen, NULL, wmanager);
+    else
+        workspace_changed_cb(wmanager->priv->wnck_screen, wmanager, NULL);
     
     wmanager->priv->inited = TRUE;