<html><head><title>Esempio</title></head><body>
<script type="text/Javascript">
<!--
function Mostra() {
document.getElementById("secondoDiv").style.visibi lity="visible";
}
function Nascondi() {
document.all.secondoDiv.style.visibility="hidden";
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</script>
<div style="position: absolute; top: 10px; left: 10px; width: 100px; height: 100px; background-color: green; z-index: 1;" onMouseOver="Mostra();" onMouseOut="Nascondi();"><font style="color: white; font-weight: bold;">Passa il mouse qui sopra</font></div>
<div style="position: absolute; top: 40px; left: 180px; width: 60px; height: 50px; visibility: visible; z-index: 2; background-color: #CCFF00 ; "><font style="font-weight: bold;">z-index:2
<select style="visibility: visible;" id="tendina"><option>Questo elemento</option><option>ha z-index:2</option><option>e questa volta</option><option>finisce sotto</option></select></font></div>
<div id="secondoDiv" style="position: absolute; top: 10px; left: 150px; width: 200px; height: 200px; background-color: red; visibility: hidden; z-index: 3;"><font style="color: white; font-weight: bold;">Secondo div (z-index:3)</font></div>
</body></html>