Drupal form elements such as checkboxes and radio buttons are all rendered using the theme system and consequently, can be overridden just like any other theme function. In this recipe, we will be adding a new feature to the
FIELDSET element by overriding
theme_fieldset(). We will be demonstrating its use by adding a postscript to the Revision information fieldset present in every node form.
This recipe requires the use of the mysite module created earlier in this book. The Devel and Theme developer modules will also be used to identify the theme function to override.
Firstly, we need to identify how Drupal is going about theming a fieldset. The recommended method of doing so is to ...