Software KVM that works on linux, OSX and Windows

I was using Teleport for Mac as my KVM. But I could only control a mac mini and my laptop with it. I was looking for something that would work with Ubuntu and MacOSX switching the keyboard and mouse between them.

I found Synergy Plus that was exactly the software KVM for my purpose. (There is also an older project called Synergy, but Synergy Plus is the latest copy being managed on google code.)

Setting up my Ubuntu machine as the server and my OSX laptop as a client was facilitated by

Configure Synergy in six steps

Use synergy between OSX and linux

One issue I had was using a PC keyboard with OSX (since my Ubuntu server is the synergy server). I was not able to map the Super key to be theCommand key. Tried various options with keymapping on Ubuntu without much success. Resolutions welcome.