Reigel's demo page

HTML

<iframe id="tail"></iframe>
<br>
<div>
    <a href="#"> This is a test link!
    <br>
    iframe should not pass over the link area
    <br>
    to avoid the iframe interpose the link! 
    </a>
    <br>
    <br>
   <input type="text" />
</div>
<br>
<a href="#"> This is a test link!
    <br>
    iframe should not pass over the link area
    <br>
    to avoid the iframe interpose the link! 
</a>

CSS

#tail {
    position: absolute;
    float: left;
    text-align:center; 
    width:40px; 
    height:20px;
    background-color:#CCCCCC;
    border:0;
    display: inline;

}

div { border:2px solid;text-align:center;} 

body { text-align:center; }

JavaScript

$(document).bind('mousemove', function(e){
    $('#tail').css({
       left:  e.pageX - 20,
        top:   e.pageY - 11
    });
});

$('a, input').live("mouseenter", function() { 
  $('#tail').hide(); 
}); 
$('a, input').live("mouseout", function() { 
  $('#tail').show(); 
});