One of the things that has annoyed me about Mac OS is the behaviour of the Tab key. When presented with a dialog box with multiple buttons, pressing the Tab key will not allow you to shift focus from one button to the next. Thankfully this default behaviour can be changed.
Figure 1: Dialog box with Tab key disabled
In System Properties, open the Keyboard & Mouse settings and click on the Keyboard Settings section. At the bottom of the screen is an option for Full Keyboard Access.
Figure 2: System Properties – Keyboard & Mouse – Keyboard Shortcuts
In this section there is the option for using the Tab key to move focus between a) Text boxes and lists only, or b) All controls. Click the radio button for the second option, and the Tab key will now allow you to tab between all the available dialog box buttons. On a MacBook you can also use the following shortcut key to turn on/ off this behaviour: ^fn F7
Figure 3: Dialog Box with Tab Key Enabled
Once this option has been enabled you should be able to use the Tab key to highlight any of the available buttons. One word of caution though: if you select a different button than the already highlighted default, then you must use the spacebar to “press” it. Using the Enter or Return keys will always “press” the default button.