Apple Final Cut Pro 6 - Manual (Page 770)

Chapter 24 Matching Frames and Playhead Synchronization 437
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4 In either the Viewer or the Canvas, choose Gang from the Playhead Sync pop-up menu.
5 Move the playhead in the Timeline to the In point of the last clip in the sequence.
The playhead in the Viewer moves to the left by the same amount.
6 In the Viewer, press O to set a new Out point.
The clip in the Viewer is now shorter by the duration of the last clip in the sequence.
This is just one example of how you can use playhead sync relationships between the
Viewer window and the Canvas and Timeline windows.
The playhead is moved
to the In point of the last
clip in the sequence.