code: public void setTrigger(final DialogOpenTrigger trigger) {
  		// pre-1.2.3 compatibilty only:
  		if (this.hasLegacyTriggerButton()) {
  			DialogOpenTrigger theTrigger = getTrigger();
  			if (theTrigger instanceof WButton) {
  				remove(theTrigger);
  			}
  			setLegacyTriggerButton(false);
  		}
  		// end of backwards compatibility code.
  		getOrCreateComponentModel().trigger = trigger;
  	}
docs: Set the component which will open the WDialog.
  
  @param trigger the WComponent which will open the dialog on click/change