Index: gtk/gtknotebook.c
===================================================================
--- gtk/gtknotebook.c	(Revision 20269)
+++ gtk/gtknotebook.c	(Arbeitskopie)
@@ -4628,7 +4628,10 @@ gtk_notebook_paint (GtkWidget    *widget
     }
   gtk_paint_box_gap (widget->style, widget->window,
 		     GTK_STATE_NORMAL, GTK_SHADOW_OUT,
-		     area, widget, "notebook",
+		     area, widget,
+		     (showarrow && notebook->scrollable)
+			? "notebook_show_arrow"
+			: "notebook",
 		     x, y, width, height,
 		     tab_pos, gap_x, gap_width);
 
