About Docker window currently only the shows the version of the Docker for Mac release. At the time of this writing, 1.11.0-beta6.
The docker engine itself, however, is on version 1.11.0-rc3:
docker version Client: Version: 1.11.0-rc3 API version: 1.23 Go version: go1.5.3 Git commit: eabf97a Built: Fri Apr 1 23:33:49 2016 OS/Arch: darwin/amd64 Server: Version: 1.11.0-rc3 API version: 1.23 Go version: go1.5.3 Git commit: 9b9022a Built: Mon Apr 4 15:24:07 2016 OS/Arch: linux/amd64
It would be nice if those two versions would show up together.