Can the PowerBook G4 operate properly with the lid closed?
Yes. According to Apple, the PowerBook G4 series can operate properly with the lid closed, which is useful if you wish to setup a “workstation” for your PowerBook G4 with an external monitor, keyboard, and mouse. Apple also mentions that with the lid closed, “you cannot utilize video mirroring. . . [with] both a VGA and S-video source connected to the PowerBook, it shows an image only on the VGA device.” So if you want the display “mirrored” on another display, such as a projector screen for a presentation, you will need to keep the PowerBook open. However, you can use an external monitor with the PowerBook G4 closed, provided that it is powered by the included AC adapter.