Editor: Window > Navigator
1, 2, 3, 4, 5
The Navigator palette is a small scalable preview palette that shows the entire image together with a highlighted rectangle (1) the size, scale and shape of the area currently displayed in the document window (2).
A new frame can be drawn (scaling the image window with it) by holding the Command/Ctrl keys and making a new marquee. The frame can be dragged around the entire image with the Hand tool.
The Zoom tools (3) can be clicked, ...