function parentClick() {
    if (document.getElementById('parentButton').value == "true" )
	{
	    document.getElementById('parent').style.display='';
	    document.getElementById('parent0').disabled=false;
	    document.getElementById('parent1').disabled=false;
	    document.getElementById('parent2').disabled=false;
	}
    else
	{
	    document.getElementById('parent').style.display='none';
	    document.getElementById('parent0').disabled=true;
	    document.getElementById('parent1').disabled=true;	
	    document.getElementById('parent2').disabled=true;	
	}
}