Yeah I agree that would be nice. I had to remove that feature because it didn’t work cross-browser after Firefox removed support for the more powerful but Firefox-specific drop-down feature. I can’t recall which browsers supported the feature now, nor to what extent but I know it was too limited in comparison to what was possible with the old add-ons system before Firefox 57.
Hopefully browsers will catch up one day; failing that, I’ll probably rewrite the whole dialog in a year or two so that a drop-down is no longer required.
Thanks for the feedback.