variable fonts and stretchy characters

Hi everyone,

Below is a video of a talk by John Hudson (of Tiro) pondering variable
fonts for stretchy constructions (the part starts around 43 min into the
talk though the link should take you there).

I've reached to John to get more input on this ideas.

Best,
Peter.

https://www.youtube.com/watch?v=MuuAmG_qer8&feature=youtu.be&t=2559