I have searched the internet for how to do this. There are are two ways.

1. Secret-shortcuts, they are:

Don't save: Command-D Cancel: Command-. or Esc Save: Return (assuming it's the default)

2. Tabbing:

Goto System Preferences Select "Keyboard and Mouse" Select the tab "Keyboard Shortcuts" Towards the bottom of this window, there is the option for "Full Keyboard Access" -- set this to "All Controls" Example: Done!