Penwidth

[Duartemartins]

Would it be possible to add this attribute?

https://graphviz.org/docs/attrs/penwidth/

[monora]

Would it be possible to add this attribute?

I guess yes. See lib/rgl/rdot.rb . This refers to an old version of the documentation from 2008.

The new version http://www.graphviz.org/pdf/dotguide.pdf from 2015 includes penwidth and many others. Would you mind creating an issue to update to the new version? And even better create a pull request...