Chiedo scusa, eccolo:

codice:
<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>Documento senza titolo</title>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.1/jquery.min.js"></script>


<script type="text/javascript"> 
$(document).ready(function(){
	
  $("#flip").mouseover(function(){
    $("#pannello").slideDown("slow");
  });
  
  $("#pannello").mouseout(function(){
    $("#pannello").slideUp("slow");
  });
  
});
</script>
 
<style type="text/css"> 
#flip
{
padding:5px;
text-align:center;
background-color:#e5eecc;
border:solid 1px #c3c3c3;
}
#pannello
{
padding:50px;
display:none;
background-color:#cecece;
}

.uno
{
width:100px; height:50px;
background-color:#ff0000;
}
</style>

</head>

<body>
<div id="flip">Click to slide down panel</div>
<div id="pannello">Hello world!

<div class="uno">Altro div</div>

</div>
</body>
</html>