The 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.