I ran into a problem where the container does not start after 10 startups. The reason for this is `/tmp/.X10-lock` file are not deleted when running `docker stop`. On next `docker-start`, `/tmp/.X11-lock` is allocated instead. This keeps going until `/tmp/.X19-lock` and from that it gives up. Another workaround is to use `--tmpfs` in `docker run`. But not all users always use it.