var timer, i, menuId; 

var dom = document.getElementById ? true : false;
var ie4 = ((document.all) && (!dom)) ? true : false;
var ns4 = document.layers ? true : false;
var opera = navigator.userAgent.indexOf('Opera') != -1 ? true : false;
var dhtml = dom ? true : ie4 ? true : ns4 ? true : false;

function writeStyle(dhtml){
	if(dhtml) document.write ('<link rel="stylesheet" href="css/menu.css" type="text/css" media="screen" />');
}


function setVisibility(element,newVisibility){
  document.getElementById(element).style.visibility = newVisibility;
}
  
function showMenu(id) {
  clearTimeout(timer);
  for (i = 1; i <= 4; i++) 
    if (i != id) setVisibility('jsmenu' + i,'hidden');
  setVisibility('jsmenu' + id,'visible');
}

function hideMenu(id) {
  menuId = 'jsmenu' + id;
  timer = setTimeout("setVisibility(menuId,'hidden')",50);
}

function dontHideMenu() {
  clearTimeout(timer);
}