// toggle classname, usually used to show/ hide elements
function cc_addRemoveClassName(obj,className,on) { // can be supplied with a html element, an id or a class
    if(typeof(obj)=="string") {
        var o = document.getElementById(obj);
        if(o) cc_addRemoveClassNameFn(o,className,on);
        else {
            objArray = getElementsByClassName(obj);
            for(var i = 0; i < objArray.length; i++) {
                cc_addRemoveClassNameFn(objArray[i],className,on);
            }
        }
    }
    else cc_addRemoveClassNameFn(obj,className,on);
}
// slave function to above
function cc_addRemoveClassNameFn(obj,className,on) {
    if(!obj) return;

    var GREP = new RegExp("\s*"+className,"g"); // look for classname, with or without preceding space
    obj.className = obj.className.replace(GREP,"");
    if(on) obj.className += " "+className;
}