Connecting extra signals to predefined widgets

[HRahman10 aol com]

I need to add new signals to the GTK+ File selector operation buttons.  I 
checked the GTK faq page and found the following code, but I am not sure how 
to use it.  The signal i want to add to the three buttons (create dir, delete 
file, rename file)  is to make the dialogs which open when the buttons are 
pressed, modal.  This is because i've added some extra buttons to the file 
selector widget, and these can be used while the other dialogs are open. 

static guint signal_user_action = 0;

signal_user_action =gtk_object_class_user_signal_new (gtk_type_class 
(GTK_TYPE_WIDGET),"user_action",
                                                                              
     GTK_RUN_LAST | GTK_RUN_ACTION,
                                                                              
     gtk_marshal_NONE__POINTER,
                                                                              
     GTK_TYPE_NONE, 1,GTK_TYPE_POINTER);

voidgtk_widget_user_action (GtkWidget *widget,gpointer   act_data)
{
  g_return_if_fail (GTK_IS_WIDGET (widget));
  gtk_signal_emit (GTK_OBJECT (widget), signal_user_action, act_data);
}   


Does anyone know how to use this code in my case, or won't this work.  And I 
don't want to mess around with the source code.