I have been thinking about this for along time to keep people from messing up installs. I was thinking of a startup script that runs in the background when a user logs on and checks periodically. The more I thought about this and the time needed to run, which I thought every 10 seconds would be good, might slow down lower end machines. I was just thinking of having sed run on the apt folder with the source files in it and remove the lines from the text file. That would not stop people from adding it from command line but might be fast enough to stop them from actually doing some damage. Just throwing out ideas and the grep command could be added to any custom startup script to hide it if necessary, so it doesn't get unchecked from startup.
