var bNetscape4plus = (navigator.appName == "Netscape" && navigator.appVersion.substring(0,1) >= "4");
var bExplorer4plus = (navigator.appName == "Microsoft Internet Explorer" && navigator.appVersion.substring(0,1) >= "4");
if (navigator.userAgent.indexOf('Safari') >= 0){
var bSafariplus = 1;
var macos = 1;
}
 if (navigator.appName == 'Opera'){
var bOpera4plus = 1;
}



function cacher(objet)
{
document.getElementById(objet).style.visibility= "hidden";
if (bExplorer4plus){
	if (document.getElementById('menu_renvoi') != null) {
		document.getElementById('menu_renvoi').style.visibility = "visible";
  }

	
}
}

function voir(objet)
{

//document.getElementById('para').value = document.getElementById('b'+objet+'b').offsetLeft+' '+document.getElementById('menu').offsetLeft+' '+document.getElementById('menu').offsetWidth+' '+navigator.userAgent.indexOf('Safari');

document.getElementById(objet).style.visibility = "visible";
//alert(document.getElementById('b'+objet+'b').offsetTop+' '+document.getElementById('b'+objet+'b').offsetParent);


//document.getElementById(objet).style.top = document.getElementById('menu').offsetTop/2 +20;
//if (bExplorer4plus || bSafariplus || bOpera4plus){
document.getElementById(objet).style.left = document.getElementById('b'+objet+'b').offsetLeft  ;
	
//}else{
    
    	//document.getElementById(objet).style.left = document.getElementById('menu').offsetLeft - document.getElementById('menu').offsetWidth/2 + document.getElementById('b'+objet+'b').offsetLeft - 30  ;
    	
    	
    	//document.getElementById(objet).style.left =   document.getElementById('b'+objet+'b').offsetLeft + document.getElementById('menu').offsetLeft - document.getElementById('menu').offsetWidth;
    
		
	//}
}





<!-- Begin
function NewWindow(mypage, myname, w, h, scroll) {


var winl = (screen.availWidth - w) / 2;
var wint = (screen.availHeight - h) / 2;
winprops = 'height='+h+',width='+w+',top='+wint+',left='+winl+',scrollbars='+scroll+',resizable,status'
win = window.open(mypage, myname, winprops)
//if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}
function fullscreenwindow(mypage, myname,scroll,status) {


winprops = 'scrollbars='+scroll+',fullscreen=1,resizable,status='+scroll;
win = window.open(mypage, myname, winprops)
//if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
}