function getElementsByClass( searchClass, domNode, tagName) {
if (domNode == null) domNode = document;
if (tagName == null) tagName = '*';
var el = new Array();
var tags = domNode.getElementsByTagName(tagName);
var tcl = " "+searchClass+" ";
for(i=0,j=0; i<tags.length; i++) {
var test = " " + tags[i].className + " ";
if (test.indexOf(tcl) != -1)
el[j++] = tags[i];
}
return el;
}

function showSubMenu(elemId) {
if (document.getElementById(elemId).style.display == 'block') {
document.getElementById(elemId).style.display = 'none';
}
else {
var tabs = getElementsByClass('tab');
for(i=0; i<tabs.length; i++)
tabs[i].style.display = 'none';
document.getElementById(elemId).style.display = 'block';
}
}