How to implement serialization of fields of the Form, that contains RadEditor (in order to make callback-request)? Microsoft JavaScript function WebForm_InitCallback() does it, scanning form fields and adding their values in a variable __theFormPostData. But in a case with RadEditor, it finds only <textarea> (<textarea ... id="RadEditor1ContentHiddenTextarea" style="display: none;">), that contains the initial data (loaded with page). How (before i make callback-request) it is possible to update value in <textarea> on the data from <iframe>? And what is purpose of <textarea> element?