var previousMenuId = null;
function hidePopUp(id) {
var el = document.getElementById(id);
el.style.display= "none";
}
function showPopUp(id) {
var previousEl = document.getElementById(previousMenuId);
if (previousEl != null) {
hidePopUp(previousMenuId);
}
previousMenuId = id;
var el = document.getElementById(id);
if (is_mozilla) {
                el.style.position="absolute";
el.style.left = mousePos.x+"px";
el.style.top = mousePos.y+"px";
}
else {
el.style.pixelLeft = mousePos.x;
el.style.pixelTop = mousePos.y;
}
el.style.display = "block";
}