Hmm. I think that's not really easy to do.
Could you post your code (the one you insert) and the code that is outputted after you save?

Trying to get these two bits of code working, and so far all suggestions of commenting lines out aren't working... (trying to integrate another php based application into silverstripe in a simple fashion.

<script language="JavaScript">
<!--
function autoResize(id){
var newheight;
var newwidth;

if(document.getElementById){
newheight=document.getElementById(id).contentWindow.document .body.scrollHeight;
newwidth=document.getElementById(id).contentWindow.document .body.scrollWidth;
}

document.getElementById(id).height= (newheight) + "px";
document.getElementById(id).width= (newwidth) + "px";
}
//-->
</script>

<iframe src="../helpdesk" width="100%" height="200px" id="iframe1" marginheight="0" frameborder="0" onLoad="autoResize('iframe1');">
<p>Your browser does not support iframes. Please contact IT.</p>
</iframe>

Hi.

I'm not sure if its tinymce or what that is causing onmouseover and onclick actions still to be stripped from my html code.

I have made all the suggested changes the banal put in

eg:

Oh yeah, a small addition to my previous post and something that will help both Daniel and Thomas:
The culprit here is the jsparty/tiny_mce_improvements.js file. There you'll find the sapphiremce_cleanup function that seems to clean up content in addition to the cleaning performed by tinymce. So.. in addition to allow certain elements (using valid_elements) or setting verify_html to false, you must change the tiny_mce_improvements.js file:

To enable onclick on links, you should remove (comment out) this line:

value = value.replace(/([ \f\r\t\n\'\"])on[a-z]+=[^ >]+/ig, "$1");

To allow blocks of JavaScript, you have to allow comments by removing the following line:

// Word comments
value = value.replace(new RegExp('<(!--)([^>]*)(--)>', 'g'), "");

but I still cant get any actions to remain in my tags like

<a onmouseover="popup('This explains nothing, but shows off something.')">this is mine</a> is still stripped to

<a>this is mine</a>

and

<a href="images/image-1.jpg" rel="lightbox"><img src="images/thumb-1.jpg" width="100" height="40" alt="" /></a>

is still striped to

<a href="images/image-1.jpg"><img src="images/thumb-1.jpg" width="100" height="40" alt="" /></a>

I'm using Silverstripe 2.4.7 and I have swfupload and dataobject-manager included

An help would be greatly appreciated.

Cheers