Netbeans 7.3's support? It works fine on Java 6, though it will only grudgingly use it if 7 is installed. If you're on MacOS (assuming that from the retina screen), then, in /Applications/NetBeans/NetBeans 7.3.app/Contents/Resources/NetBeans/etc/netbeans.conf
BTW Git diffing between revisions is very cool, I used to have some custom scripts which would call meld to do that.