hbox.pack_end(button, FALSE, FALSE, 0);
button.connect( "clicked",
G_CALLBACK( dialog_button_callback ), GINT_TO_POINTER( IDOK ) );
hbox.pack_end(button, FALSE, FALSE, 0);
button.connect( "clicked",
G_CALLBACK( dialog_button_callback ), GINT_TO_POINTER( IDOK ) );