Unpredictable things will happen if the data file has too many spaces between the data columns. The data will not be read in correctly. Commas and other delimiters are way out. Data sets are limited to 500 pairs of points. Hmm, something to change for the next version.
Saving is peculiar.
I could if I clicked in the data's display window. So, if you try to save from the menu, you'll get a reminder to click in the data window. If you abort a save process, the system will hang up. I haven't put in any error checking for this case. The data screen gets filled with garbage.