PostScript stem hints

In our Glyphs source we defined alignment zones (bluezones) for all masters and put in stem hints in one master. Glyphs can propagate those instructions to the other masters and instances on export ('Get hints from master' custom parameter). But when building with FontMake, I see the hinting is discarded, perhaps because we didn't explicitly define hints on all masters? We can easily apply the hints to all masters in the .glyphs source but would it be possible for FontMake to do this automatically with an option to also 'get hints from master'?

No files or tests are named. Start by tracing how FontMake reads Glyphs sources and handles PostScript hints during export, then identify where an option could apply hints from one master to other masters and instances. Done means the option is defined, documented, and verified to preserve the requested hints in the generated fonts.

Written by the indexing model from the issue text.