Along the same lines, so worth mentioning, while expirimenting with <script> functionality in the editor, I made a very simple page, as follows:
<input id=Button1 onclick=BLOCKED SCRIPTclickthis() type=button value=Button1 name=Button1>
<script language='javascript'>
function clickthis()
{
alert("help!!!");
}
</script>
It doesn't work in Preview mode, and when I view source on the editor Iframe, this is what the rendered code looks like:
<html>
<head>
</head>
<body>
<input id=Button1 onclick=BLOCKED SCRIPTclickthis() type=button value=Button1 name=Button1><body>
</html>
It looks like the <script> tags got replaced with whatever that is in red.