Sorry, I am making a habit of posting questions and answering them myself – the bottom boxes are box-tl etc (the clue is in the name).
just so this post is not a complete waste of time can I recommend the ‘aardvark’ and ‘developer’ extensions for firefox. I find them consistently useful, aardvark is especially useful when modifying other peoples’ templates as it quickly identifies div tags for you, Developer does a whole host of thinks, including giving you the name of all the images and background images on the screen, making it really easy to find and replace template images.
bye!