D7 Theme Dev: $head_title undefined in page.tpl.php

I know that $head_title is defined in html.tpl.php, but if I define a function its not defined in this file; no idea why; but this is my problem.

What I want to do is define a function or class, in preprocess_page, then its available to page.tpl.php, works fine, but its not available to html.tpl.php; which is the problem; I need to pass in variables before I execute this function; so I can set css and js based on other settings.

I'm trying to fix my D7 theme, it worked during alpha; but now is broke; seems drupal_add_html_head is not working as it did then; any ideas why?

Thanks for any help in converting D6 to D7; or finding any docs that might help.