code: public void setDateFormatString(String dateFormatString) {
  		if (ignoreDatePatternChange) {
  			return;
  		}
  
  		try {
  			dateFormatter.applyPattern(dateFormatString);
  		} catch (RuntimeException e) {
  			dateFormatter = (SimpleDateFormat) DateFormat.getDateInstance(DateFormat.MEDIUM);
  			dateFormatter.setLenient(false);
  		}
  		this.datePattern = dateFormatter.toPattern();
  		setToolTipText(this.datePattern);
  		setDate(date, false);
  	}
docs: /*
  (non-Javadoc)
  
  @see com.toedter.calendar.IDateEditor#setDateFormatString(java.lang.String)