/*--------------------------------------------------------------------
    * Function:    button_messages
    * Returns:     t or nil
    * Description: Calls send_message() for 3 button callbacks.  This
    *              function is used only in GTK-specific code, so there is
    *              no Photon counterpart. The "clicked" callback is only
    *              strictly necessary for the radio buttons in the Monitor.
    *------------------------------------------------------------------*/
   function button_messages (button, msg1, msg2)
   {
     button.signal("enter", `send_message(@msg1));
     button.signal("clicked", `send_message(@msg1));
     button.signal("leave", `send_message(@msg2));
   }