Editing : Edit Modes and Tools : Zoomer Tool

Zoomer Tool
For more information, see the following topics:
Use the Zoomer tool to zoom in and out around a particular area within a track.
The Zoomer tool offers two modes:
Normal Zoom
The Zoomer tool remains selected after zooming.
Single Zoom
The previously selected Edit tool is automatically reselected after zooming.
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Press the F5 key to select the Zoomer tool and toggle between Normal and Single Zoom modes.