I've got a pagetype called Map.php and it uses the default Page.ss Template and an adjusted Layout.
Now I made a copy of Map.php (Map_FB.php which extends Map.php) and made a Map_FB.ss in my templates folder.
That way I can remove the header and footer and put that Map into an iFrame on Facebook.
But the page I created in the CMS still uses the default Page.ss template, not the Map-FB.ss template file.
I flushed the cash, deleted the file and recreated it. But with ?showtemplate=1 it shows me SS uses the page.ss file.