Stop fieldset from collapsing

Stop collapsible fieldsets from collapsing by removing the collapse functionality on particular fieldsets.

Snippet:

<?php
// into your template.php file
// this example works on the signup form (from signup.module)

function phptemplate_signup_form($form){
    $form['collapse']['#collapsible']=false;
    return drupal_render($form);
}
?>