title: How To: add dynamically HiddenField in masterpage base page
body: <p>I have a Base MasterPage class, from which my masterpages will inherit. I have some javascript functions there for it's child pages to include. As it's a base class, it does not have a visual designer nor I can add XHTML code.
  I need to add a hidden field to the class so I can set it's value in the javascript code, and when a postback occurs I can get the setted value on my content pages.
  Yet I fail to achieve this, for when I try to add the hidden field to the base masterpage's control collection I get a render error (Content Encoding error if viewed in Firefox). And If I try cheating and registering a hidden field via scriptmanager with the same name in stead of adding the control to the control collection, well... I get the value as empty.
  How could  achieve this?</p>