Ability to collapse "rare" combinations in the presets

[openstreetmap.org-user-d1g]

I was reading about osmagent approach (quote below) and decided to discuss if it would be good to implement it in JOSM

• display rare keys (covered, cutting, et.c.) below other keys
• collapse/uncollapse them all using UI; I suggest label them as "less common combinations"

we could use

​osmagent:
I.e. the app will never ask users "Is this footway covered?" because while covered=yes might be a valid extension of the tagging of a footway, it only applies to a overwhelming minority of all footways.

On the other hand, the majority of all shops will have fixed opening hours, so the app will ask users "What are the opening hours of this shop?" and so on.