I would find it really convenient if, when drawing closed lines, one had an option, that only the fill pattern gets drawn, but that the "empty space" of the fill pattern shows "what is below".
For example, it would be helpful if one cross out something drawn with the diagonal fill pattern.
I also wish winfig was better at remembering which way I exported a file. For instance, I usually use pstex, but winfig always forgets what magnification I used.
Having said that, winfig is really a great tool. I have used it for an endless number of lecture notes.