Hej Rune
Here are some more ideas.
Loading (importing) S-files. Try to identify the source program, but also show the first five, or a bit more, lines of the file. Then ask the the user to confirm the source program/format from a number of radio buttons.
Adding tooltips can perhaps improve the usage/understanding of the various buttons and input fields.
To the right of the sweeps write the Hz/div. and dB/div.
Bo
Bo, OZ2M