// Gets all the elements with the class name and places them in an array
document.getElementsByClassName= function(cl) {
	var retnode = [];
	var myclass = new RegExp('\\b'+cl+'\\b');
	var elem = this.getElementsByTagName('*');
	for (var i = 0; i < elem.length; i++) {
		var classes = elem[i].className;
		if (myclass.test(classes)) retnode.push(elem[i]);
	}
	return retnode;
}

// Updates the style display value for all elements of a class name 
document.updateClassDisplay= function(cl,disp) {
	var i, n_elems, elems = document.getElementsByClassName(cl); 
 	n_elems = elems.length;
 	for (i = 0; i < n_elems; i++){
 		elems[i].style.display=disp;
 	}
}