Relations: missing search criteria

On 5.7.3-SNAPSHOT, the document search in relations now uses select2.
I'm missing some information and features:

• there is no way to distinguish published documents from workspace documents (previous search screen had a "path" column in search results)
• I found it nice to be able to restrict the search to a certain path
• it displays only a limited numbers of documents and if the one you look for is not in it, you can't create the relation.
  For instance on the intranet, I was looking for a note called "AFP", and when I type "AFP" in the select2 box, it's not displayed. It's frustrating to type the title and not find the document. I need to type additional words from the description or content to find it.

Possible improvements:

• Add a link next to the select2 box that displays an "advanced" search form with a limited set of criteria (like we had on 5.6).
• Maybe change the sort criterion of search results? (I don't know what's the current criterion.)