Did you install Developer Support ( acs-developer-support package)?
Recently was added an 'ADP reveal mode' to Developer Support that could be very useful to help you trace the file name in pages. I think you want to download it from HEAD - i'm not sure if changes was made to other branches.
After you install DS you will see the "ADP" link in the developer bar. Click on it and files will be revealed to you. it is a very nice feature.
Hope it helps.
