Comment 9 for bug 172063

I do two diferent XOR attemps. Is just base code for BPaths (pen, pencil helper lines and more).
I attach here with a test SVG I made.
No one of both is perfect, but I spend a lot of time finetuning it, I think is dificult get too much better display.
The bad thing: It slow the dreawing process and seems dificult to fix because it render the down drawing in each movement. Maybe we finaly need to say goodby to XOR or Difference BPaths because his slowest, and going to previous patch well implemented in each canvas item.