Apple has posted a Knowledge Base article (#86286) that explains how to use your MacBook Pro with the display closed, it also works with the PowerBook G4.
Basically it boils down to closing the computer’s lid once your computer’s desktop appears on the external display. When the lid is closed, wake the computer up by either clicking your mouse button or by pressing a key on your keyboard.
If you want to do the same thing with a Bluetooth mouse and keyboard, see KBase article #.

Apple has posted a Knowledge Base article (#86286) that explains how to use your MacBook Pro with the display closed, it also works with the PowerBook G4.
Basically it boils down to closing the computer’s lid once your computer’s desktop appears on the external display. When the lid is closed, wake the computer up by either clicking your mouse button or by pressing a key on your keyboard.
If you want to do the same thing with a Bluetooth mouse and keyboard, see KBase article #.