Once you’ve picked your photos, set your options, and selected a music track, your show is ready to run. Click the Play button (the triangular button beneath the Source list) in the main iPhoto window. The slideshow begins instantly.
iPhoto slideshows run themselves, advancing from photo to photo according to the timing you set in the Slideshow dialog box. However, you can control a slideshow after it starts running in a number of ways. Some of these functions are also represented by icons on the control bar (see page 95), but it’s nice to know that you can also trigger them from the keyboard, with or without the control bar:
Pause it. Press the Space bar at any point to pause a slideshow. The music keeps playing, but the photos stop advancing. If the control bar isn’t onscreen, a glowing Pause indicator briefly appears in the lower portion of the picture. When you’re ready to move to the next slide and resume the auto-advancing of pictures, press Space again. A small Play indicator appears onscreen momentarily to confirm that iPhoto has understood your command.
Manual advance. Press the right or left arrow keys to advance to the next or previous photo, overriding the preset timing. In fact, once you hit either arrow key, the slideshow shifts into manual mode and stops advancing the photos altogether. A small translucent bar with arrows and a Play button appears onscreen to indicate that iPhoto is listening to your key presses.
At this point, ...