At bottom-right of the application window, click the Zoom Area button: 
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In the view you want to zoom in on, click the top left corner of the area you want to see.
Click the bottom right corner of the area you want to see.
Tip:
You can drag to dynamically zoom in on an area in the view.
Press the Ctrl+Up arrow keys or Ctrl+Left arrow keys to zoom in on an area.
To exit this command, click the right mouse button, press the Esc key, or select another command.