Thanks Dan for this comprehensive reply.
Pd tries to use the same standard font across all platforms as of around 0.48 or 0.49. In 0.52, we now included the italic and bold versions of DejaVu Sans Mono as well.
Highly appreciated.
The result is that if you make a patch on one system with the standard font and open it on another with the same or ver similar (macOS)-sized font, the rendering should be very close.
It was close enough indeed, except on Ubuntu 18 which makes a complete mess. It might be on my side too.
There is also a text patch with all the GUIs you can use to compare on different systems: Help->Browser : Pure Data/7.stuff/tools/sizingtest.pd
This is good to know - I now have Parallels running with Windows10 and Ubuntu20 in MacOS so I can see in realtime what they look like.
I would also ask Alex and the cyclone team as they have deployed a standard help-file format and pushed for some of the required changes in this area.
Oh that is a great pointer - I’ll try to reach for him as I’d like to get it right (or at least get challenged by their requests :) - I presume they opened a project/pr on GitHub? I’ll check them out.
Oh, one thing I've forgotten about: the default font is bold on Windows and Linux which normal weight on macOS.
I read about it and it looks a bit different but not enough to cause issues with Menlo/DejaVu
Thanks again for the extensive response!