This is how I set configuration on PHP-Eclipse to know file.thtml.
first open menu in eclipse as you see in this picture below ( Window -> Preferences ),

after that you see on the TREE MENU click on “Content Types” and on the Right-Top, click “PHP Source File”, see the Right-Box Below and Add “File Associations” for “*.thtml”

on the TREE MENU click on “Editor – File Associations” add File Types:*.thtml and set Associated Editor to “PHP Editor”.

December 17, 2006 at 10:52 pm
nice… just one thing to add
restart eclipse to get the color coding working on the thtml files. Took me a bit to figure that out…
August 30, 2007 at 5:41 pm
[...] Par défaut le plugin php-eclipse n’est pas utilisé pour les fichiers .thtml de CakePHP, donc pas de coloration syntaxique et pas de complétion. Pour rajouter les fichiers .thtml, c’est très simple il suffit de suivre ce tuto. [...]
August 12, 2009 at 12:47 pm
thnks for this. I was looking for the way out.