windowManager: Don't use show_all

It is deprecated and does not make sense there anyway, so use show() instead.

https://bugzilla.gnome.org/show_bug.cgi?id=694441

js/ui/windowManager.js

@@ -593,7 +593,7 @@ const WindowManager = new Lang.Class({
                 switchData.windows.push({ window: window,
                                           parent: window.get_parent() });
                 window.reparent(switchData.inGroup);
-                window.show_all();
+                window.show();
             }
         }