GFI: Potentially irritating behaviour in feature list

[warm-coolguy]

Describe the bug

The GFI's feature list will, on high zoom levels, at times display a feature list with a single entry, despite a blue multi-marker indicating multiple features is present. This is confusing to users, as they only see one entry, but apparently multiple features in the map.

This results of blue multi-markers resulting from active and inactive features combined, but the feature list will only display active features.

Expected behavior

We just don't know. We have no idea how to resolve this properly. We also don't remember why isSelectable is a feature at all.

Steps to reproduce

1. Zoom in and pan around until you find a multi-marker that has but one feature list entry

Screenshots

Desktop

Any

Smartphone

Any

Additional context

This issue stems from the discussion in #447 (comment); we continued it by ☎️, but didn't come to conclusive results. It does not matter practically at the time being, but is kept as an issue for future rework.

[warm-coolguy]

@dopenguin I reduced priority to Low since disabled markers are currently not required. Maybe I'm wrong, in that case change it back.