Once again through nuttn it out the solution i have found seems to be quite basic and easy, but if any one knows a easy way to do this then please post it.
Solution:
I just created a hidden text box on the parent and when i clicked the button to pop up the child, i created a function which inserted the editor text into the hidden form feild then accessed it from the child.
In Parent Page
<input type='hidden' name='HTMLPreview'>
In Child Page
document.getElementById('foo').innerHTML = window.opener.document.form1.HTMLPreview.value
Regards.