diff -r -u gdm-2.28.0.orig/gui/simple-greeter/gdm-option-widget.c gdm-2.28.0/gui/simple-greeter/gdm-option-widget.c
--- gdm-2.28.0.orig/gui/simple-greeter/gdm-option-widget.c	2009-09-27 19:06:18.936241466 +0200
+++ gdm-2.28.0/gui/simple-greeter/gdm-option-widget.c	2009-09-27 19:06:59.729242474 +0200
@@ -905,6 +905,7 @@
         gtk_box_pack_start (GTK_BOX (box), widget->priv->label, FALSE, FALSE, 0);
 
         widget->priv->items_combo_box = gtk_combo_box_new ();
+        g_object_set( G_OBJECT(widget->priv->items_combo_box), "has-frame", FALSE, NULL);
 
         g_signal_connect (widget->priv->items_combo_box,
                           "changed",