As Chris Marie points out, you can set it (at least in Producer) to show the upper layer name. Note that you can also name a slide (in slide options). One of the problems with trying to show the file name on the time line is that many slides will often have multiple layers (made up of multiple images) - this is especially true of a slide that has a style applied that has say 4 images in it. Which one do you use to display on the timeline? Some slides can have 20 or more layers made up of multiple images and masks (which may also be an image). What to display becomes a real problem.
You can't have too many gadgets or too much disk space !!
mikey (PSP6, Photoshop CS6, Vegas Pro 12, Acid 7, BluffTitler, Nikon D70s, D300s, D810)
Lots of PIC microprocessor stuff too !!