I have seen a few things that if they worked a bit differently they would make some stuff a little quicker to do. I'll post suggestions as I see/remember them
Rename one of the "detail" sections. I found it very confusing that the detail under "draw" and detail across the top were not the same thing.
When going into the function window it would be nice if the window opened large enough that you can actually read the options you can choose from and/or have it save the size when you manually resize it so you don't have to resize it every time you go into it.
Also in the function window have it auto highlight what is in the box so that when you hit the little hand to move an option over or double click the option it overwrites what was there rather than having to manually delete it.
Have a global variable that saves the measurement type you want to use. So you could set in preferences that you want it always in cm or inches etc and every new project you starts starts with that automatically.
Zoom to fit best could have 2 options, 1 to zoom to show everything and one that just zooms in on the current pattern piece.