13.5. Photon: Log callbacks - start_logging

This function is necessary because we need to attach three callbacks to the Log to button, and they must be executed in the correct order. It is called by a callback on the logbut in the create_log function, and it calls the start_stop, log_toggle and send_message functions.

   /*--------------------------------------------------------------------
    * Function:    start_logging
    * Returns:     t or nil
    * Description: Coordinates callbacks for the Log to button.
    *------------------------------------------------------------------*/
   function start_logging (logbut, textwgt, fbut, sbut, anybut, fbut, allbut)
   {
     start_stop(logbut, "textlog", "tlog", "-n", "tlog", 
                 "-d", "toolsdemo", "-D", "tl.cfg");
     log_toggle(logbut, textwgt, fbut, sbut, anybut, fbut, allbut);
     send_message("nsnames");
   }