function switchMenu(obj,image) {
    var el = document.getElementById(obj);
    var imel = document.getElementById(image);
    if ( el.style.display != "none" ) {
        el.style.display = 'none';
        imel.src = 'plus.gif';
    }   else {
	el.style.display = '';
        imel.src = 'minus.gif';
    }
}