netz
netz
I assume it is the animation inside level demonstration. If that is the case, the following image would solve the issue (play animation button changes to reset button). 
I opened PR for issue [here](https://github.com/pcottle/learnGitBranching/pull/1072).
The `JAVA_HOME` environment variable is set to: ``` /usr/lib/jvm/msopenjdk-current ``` However, root privileges are required to access this directory.