JavaScript DHTML/Event onMethod/onSelectionChange
"onSelectionChange" Example
<head>
<script language="JavaScript" for=document event=onselectionchange>
alert("The selection has changed");
</script>
</head>
<body>
<p>Copy some text into the textarea</p>
<form>
<textarea cols=30 contenteditable=true>Click here</textarea>
</form>
</body>