I found that doing a subtraction is possible using a "layer binary operations", creating an auxiliary layer. But I am still confused about a "normal" subtraction.
Well, so far I have just built klayout with ASAN (it builds and even runs), and the issues I am finding are mostly memory issues, so I don't expect the patches that I might suggest (or might not) to exceed a few lines.
Concerning Centos7, are you h…