When I try to use the middle mouse button, the game does not respond as expected. Why?

By default, Mac OS X uses the middle mouse button to trigger Exposé. If you wish to use the middle mouse button as a control in the game, its default setting will need to be altered.

To alter the default setting in Lion (Mac OS X 10.7) follow the steps below:

1. Open System Preferences ( Menu → System Preferences).

2. Select Mission Control. Under Keyboard and Mouse Shortcuts, you will see the words Mission Control, followed by two drop-down menus.

3. Select the "-" option from the right-hand drop-down menu.

4. Close the Mission Control window.

To alter the default setting in Snow Leopard (Mac OS X 10.6) follow the steps below:

1. Open System Preferences ( Menu → System Preferences).

2. Select Exposé & Spaces in the Personal panel.

3. Select the Exposé tab at the top of the window.

4. Select the "-" option from the top right-hand drop-down menu in the Exposé section. Additionally, if any commands are mapped to Mouse Button 3, map them instead to the - key.

5. Close the Exposé & Spaces window.

The middle mouse button will no longer trigger Exposé and should function as expected in the game.