Forum .LRN Q&A: Re: RFC: Portlet shading
This is more a portal system issue than a theme issue, so it is not taken to the theme level.
One issue though: How is the value in my_portlet_shaded_p stored back on the server for the user, so next time he accesses the page he will see the portlet shaded (or not).
The content of the portlet is always transfered from the server to the browser and the browser decides using JS depending on the my_portlet_shaded_p (e.g. forums_shaded_p) parameter whether to display the content or not.