Runner user group can still edit cells and run and save

In the Zeppelin Notebook, when a user is put into the "runner" group, he should be able to run the cells, but not edit them and run his own code instead. This would be very useful to my team at work. 

I just tested this by logging in as a "runner" user. If I edit the cell and click the "run" button on the right, a pop up window and show. Anywhere I click, I will be taken out of the notebook to the home page. This is a little inconvenient if I hope to get back to the notebook and continue my analysis.

More importantly, if I edit the cell and hit "shift-enter" instead of clicking the "run". I'll be able to run whatever I put in, and the change will even be saved successfully, overwriting the original code. This has defeated the whole purpose of the "runner" user group!