by Lazur - uploaded on May 30, 2016, 9:46 pm
Someone asked for inverted masking over #inkscape @freenode,
so that two objects could fit with eachother perfectly.
If both masked objects were semi-transparent over eachother, the background would show through, so
made this "compositing filter" where the alpha values add up to full opaque fill.
Doubt if anything but inkscape could render it right.