> or you send them photofilms with the correct polarity. I always do > it, I do not work with gerber files, I made my own films.
If you make your own films, it's less of a problem. The only difference between the two gerbers is that one has IPPOS and the other has IPNEG; it's simple enough to edit the file and change them if needed. Plus, PCB already has an "invert" option to invert *all* the gerbers, then you can pick out the ones you want. What I'm talking about is which polarity the mask has when the other gerbers are normal. The casual user is going to do a print and send, we want that to work right as often as possible. I'll see how hard it will be to add a mask toggle though.
