In previous versions, it was possible to only display tracked quests, it doesn't seem possible anymore, or is just the feature not yet implemented ?

Not yet implemented yeah. The tracker as a whole hasn't been ported to classic yet, it's being worked on though. I wanted to get that in by sunday but that was a bit of an optimistic estimate. Now we've all gotta deal with some IRL stuff but, it will still be coming out very soon. Top priority right now

Personally would love to see it integrated with MonkeyQuest instead of porting a full tracker if it moves the rock faster.

Merging this with #681 Have a look at the latest releases of Questie to get a WIP build of the tracker.