code: protected void fireValidityChangedFor(Object changedObject, int index, BusPrimitiveInvalidity oldReason,
  			BusPrimitiveInvalidity newReason) {
  		resetBoundingBox();
  		final BusChangeEvent event = new BusChangeEvent(
  				// source of the event
  				this,
  				// type of the event
  				BusChangeEventType.VALIDITY,
  				changedObject,
  				index,
  				"validity", //$NON-NLS-1$
  				oldReason,
  				newReason);
  		firePrimitiveChanged(event);
  	}
docs: Fire the event that indicates the validity of the object has changed.
  
  @param changedObject is the object for which the validity has changed.
  @param index is the index of the changedObject in its parent.
  @param oldReason is the old invalidity reason before the change.
  @param newReason is the current invalidity reason after the change.