Drupal files have .module and .install extensions. Eclipse PHP Development Toolkit (PDT) does not recognize those extensions as PHP files so you have to tweak couple of settings to make PDT be more helpful when you develop with Drupal.

1. In Preferences - General - Editors- File Associations, associate *.module and *.install with PHP Editor.
2. In Preferences - General - Content Types, add *.module and *.install to Text -> PHP Content Type

And, of course, make a habit of using PHP Explorer, it’s much better than Navigator, for PHP projects!

cheers.