Menu popup bug?

[Gustavo Joćo Alves Marques Carneiro <ee96090 fe up pt>]

  In the example in attachment, a window with a button is
created. Clicking on the button pops up a menu. 
  When the pointer moves into the first item of the poped up menu, which
has a submenu, the submenu appears. When I move the pointer down, instead
of highlighting other menu items, the first one remains active.
  This doesn't occur if the first menu item selected doesn't have a
submenu.
  It looks like a bug, doesn't it? The question is, is it in GTK or in the
program?

-- 
Gustavo J.A.M. Carneiro
[linuxdeec.fe.up.pt/~ee96090]
                                       

#include <gtk/gtk.h>

void button_cb(GtkWidget *button)
{
    int i;
    GtkWidget *menu, *item1, *item2, *menu1;

    menu = gtk_menu_new();
    gtk_widget_show(menu);
    for (i = 0; i < 5; i++)
    {
	item1 = gtk_menu_item_new_with_label("item");
	gtk_widget_show(item1);
	gtk_menu_append (GTK_MENU (menu), item1);
	menu1 = gtk_menu_new();
	gtk_widget_show(menu1);
	item2 = gtk_menu_item_new_with_label("item2");
	gtk_widget_show(item2);
	gtk_menu_append (GTK_MENU (menu1), item2);
	gtk_menu_item_set_submenu (GTK_MENU_ITEM (item1), menu1);
    }
    gtk_menu_popup (GTK_MENU (menu), NULL, NULL, NULL, NULL, 
		    NULL, NULL);
}


void main (int argc, char *argv[])
{
    GtkWidget *window, *button;
    gtk_init(&argc, &argv);
    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    button = gtk_button_new_with_label("menu button");
    gtk_container_add (GTK_CONTAINER (window), button);
    gtk_signal_connect (GTK_OBJECT (button), "clicked",
			GTK_SIGNAL_FUNC(button_cb), NULL);
    gtk_widget_show_all (window);
    gtk_main();
}