>One other fact about html:xxx tags that's not very well documented is that >if you supply a body for the tag, it is used as if you had coded a value >attribute for that tag. Unfortunately it doesn't work for the html:hidden tag. The tld specifies that it can't have a body.
I would say the best approach here is to populate your ActionForm in the Action used to load the page. ie in java code:
Then when you forward to your jsp page with just
<html:hidden property="color"> It is automagically populated for you.