/*   
** Trigger:   WHEN-NEW-FORM-INSTANCE 
*/ 
DECLARE

   timer_id TIMER;

   one_second NUMBER :=  1000 ;

BEGIN

   timer_id := FIND_TIMER('CLOCK_TIMER');

...

/*
**WHEN-TIMER-EXPIRED 
*/
DECLARE

   timer_name VARCHAR2( 30 );

BEGIN

   timer_name := GET_APPLICATION_PROPERTY(TIMER_NAME);

   IF  timer_name = 'CLOCK_TIMER' THEN

      SELECT  TO_CHAR(SYSDATE,'HH24:MI:SS')

      INTO   :toolbar.current_time

      FROM   DUAL;

   END IF;

   EXCEPTION WHEN OTHERS THEN

      MESSAGE(TO_CHAR(SQLCODE)||''||SQLERRM);

END;