Does grapejs provide variable selection in the UI

I have just come across grapejs and it looks amazing but I cannot find good information on how to manage variables.

Is there are a way to give grapejs a list of allowed variables so the user can insert them easily through the UI when creating a template (editing text) or do they have to just type in the variable syntax where they need it, or am I expected to extend grapejs to add this functionality?

I could not see this feature in either of the demos and cannot see it mentioned in the documentation though I assumed it would be a fundamental feature.

thanks.