Relation dropdown menu should prioritize parent relations of connected features #11676
Description
The Relations section’s “Choose a parent relation” dropdown menu shows all the relations in the current viewport, sorting them by relation ID. Most users don’t have much insight about relation IDs. Instead, we should try to sort the relations by something more directly relevant to the task at hand, such as prioritizing the parent relations of connected features.
#7964 proposes to sort the most recently used relations to the top. This is helpful when building a relation by adding its members individually, but it doesn’t help when making a spot fix, such as closing a gap in a broken relation. Besides, when I’m in the middle of building out a public transportation route, I’m usually juggling two or three different relations at a time (one for each direction, plus a route master relation), which might be named similarly. These relations would swap places frequently in an MRU list, making the task quite error-prone.
The most common relation types expect all or most of the relation’s members to be connected to each other. Of the relation types that have presets in id-tagging-schema, only enforcement, public_transport, and site mostly include disconnected members.
#11588 would add any other relation the user has previously modified in the same session. This would make the list more heterogeneous, so a more intelligent sorting order would be even more helpful.