function defaultButton(e, buttonid){ 
	var bt = document.getElementById(buttonid); 
	
	var eDefined = e!= null;
	var bDefined = bt != null;
	var eventDefined = window.event != null;
	
	if (eDefined && bDefined)
	{
		if (e.keyCode == 13)
		{
			bt.click();
			return false;
		}
		else
			return true;
	}
	
	if (eventDefined){ 
		if (event.keyCode == 13){ 
				bt.click(); 
				return false; 
		}
		else
			return true;
	} 
	
	return true;
}