Sometimes after using the knife tool to slice a contour, the glyph gets confused. The wrong selection is drawn. Tracebacks are printed to the Console. When I close the ufo and reopen everything afterwards, the data is as expected (and cut). These problems don’t happen frequently, but I wonder if there might be something in the point structure that causes this to happen. So in order to gather some data for Frederik to work with, I wrote this little diagnostic script. It dumps the GLIF xml of the current glyph, and it retrieves the glyph’s xml from the UFO as well. Both are saved in a single, timestamped text file next to the UFO. So this won’t actually solve the problem, but it will save diagnostic data that might help to solve the puzzle.

Usage: for the best results, the differences between the UFO glif and the current glif have to be as small as possible. If you’re encountering slicing problems with some regularity, save the UFO before slicing anything. Then send the report to Frederik.

Note: the GLIF data is your glyph. Don’t send secret stuff. But do try to help :)