If you know TortoiseSVN on windows systems you will recognize strong similarities in RabbitVCS. It provides a nice interface which is integrated into nautilus, the default file manager in gnome.
Install it on Ubuntu/Linux Mint:
sudo apt-get-repository ppa:rabbitvcs/ppa
More information on installation of RabbitVCS can be found here:
http://wiki.rabbitvcs.org/wiki/install/ubuntu
Screenshot of RabbitVCS integration:
http://wiki.rabbitvcs.org/wiki/_media/about/context_menu.png
Logo of RabbitVCS:
http://upload.wikimedia.org/wikipedia/en/6/6e/Rabbitvcs.svg
There are some explanations for installing protege (with JDK 6 or later). But I ran into an additional problem when I tried to start the OntoGraf plugin.
If protege starts without problems (rename felix.jar or just use JDK 6 and not the latest version) but the OntoGraf plugin gives an error just install graphviz. On Linux Mint 12 you can run:sudo apt-get install graphviz
Now the plugin works without further problems.