Ok thanks - so now I have the arduino-0018.dmg file in my applications folder.
My options seem to be limited to open the file with the diskimage mounter.app, but I think you said don't do that.
So where to now.
If I do let the diskimage mounter run then I end up with the arduino.app which does run but still no sub folders for libraries, examples etc.
Clearly I am doing something wrong here or neglecting to do something right. I did manage to get v11, v13, & v16 all setup without any issues.
Is there something different with v18 ?