Switching between projects with Stackdriver query

Hi guys, as I see https://github.com/grafana/grafana/pull/22447 there’s a possibility to switch between stackdriver projects.

How should I config that?
I’ve got two projects, lets say Project A and Project B.
Both projects are added as Stackdriver data sources to Grafana (monitoring and api viewer). Both projects have enabled resource manager api too.
Project A has access to Project’s B monitoring viewer as well. (I’ve done it by adding Project’s A service account email to Project’s B IAM role, not sure if it’s correct way but I guess so)
Now, if I select Project A stackdriver as a data source I still cant see (and even cant “click”) Project B in Query Editor.

At which step have I done mistake?