Would be amazing indeed and will solve a lot of our problems.

(In reply to comment #0)
> A few problems though:
> - we currently access metadata synchronously whenever we need it. Instead, we
> need to query the available metadata async when opening the document, and keep
> the info around.
> - need to convert current stored metadata to new metadata on first run

There's another problem:

 - we currently save the last document settings in the metadata file as an special document (<document uri="last-used-value") to reuse them for new documents. Gio metadata is associated to real files. 

I think we can just use a GKeyFile in ev_dot_dir for such settings. 

However, using gio metadata is a first step to fix bug #583680, and with multiple processes the use of a GKeyFile in ev_dot_dir is a problem, so in this case we should probably go back to the old solution and use gconf again for such global settings. 

Another solution might be to use an empty file in ev_dot_dir and store the global settings as gio metadata of such file, but this looks more like a hack to me. 

I also think that we shouldn't reuse some of the settings that we currently reuse like continuous or dual view. IMO only toolbar visibility (and perhaps sidebar visibility too, I'm not sure) should be reused for new documents.

I've just committed to git master the new metadata code. The only missing thing for now is the last used setting stuff. I'm still not sure how to fix it or even if we really want it. The migration tool doesn't delete the old metadata file so it's safe to test it.

Carlos, isn't this solved by the "Save current Settings as Default" in the Edit Menu? Also, maybe this makes more sense in the View menu?

Yes, it's fixed. The View menu contains only items that affect the user's view of the current document.