var arrows0 = "model_slice/arrowR.gif";
var arrows1 = "model_slice/arrowD.gif";
function handleparent(parentID){
	myparent = document.getElementById("menu" + parentID)
	if (myparent.style.display=="none") {
		myparent.style.display = "block"
		document["arrow"+parentID].src = arrows1;
	} else {
		myparent.style.display = "none"
		document["arrow"+parentID].src = arrows0;
	}
}