@flamingspinach:
Yes, sorry for the delay here. Your comment gave me the impetus to finally address this. I partially merged some of the work from my collections branch. In picard-git there's now a collections submenu when you right-click on one or more albums. You can add/remove albums from a collection in this way. It might seem clunky, but I can always improve it based on user feedback.
The feature I didn't merge is the collections viewer, which was a separate window you could open to view all of your collections, and move releases between them. I'm mainly upset with the performance it has for large collections, not only because of web service paging when requesting the releases, but also the QTreeWidget itself, which is slow, and a terrible UI to begin with, because it's not searchable/filterable (without a custom model). I'm starting to question the usefulness of such a tool in picard. I really think a nice JS-based collections viewer/manager belongs on the MB website, not as a slow/clunky desktop app.
I'm going to close this ticket since we now have the basic functionality ("adding/removing albums to/from an MB collection"), and would prefer that people open improvements as separate tickets.
https://github.com/musicbrainz/picard/commit/994eb75c5474d6ac35a92a99c29f61d32ca0e71c
Awesome, thanks a lot!
I await the next version of Picard.