One thing that comes to mind about how a FileShark GUI should be different from a WireShark GUI is the amount of data that should / can be shown.
In my job, I often analyze ELF files. Very big ELF files. One thing I'd like to do in FileShark is to read them, look at the various headers, but not have it show me all the data in each ELF section by default. Because, they are huge, and I don't need a hexdump of megabytes of data I don't care about.
maybe it's just a matter of not using the "data" dissector.... but then again, I wouldn't want the hexdump pane to have to show gigabytes of raw data.
I think that's a key difference; wireshark will show all data, because each packet is relatively small. But there can be megabytes of data in a file that could be to difficult to show as a single "packet"
Gilbert