How to Create the Navigation Window and Work with it
Choose the command View > Full + Monitor. On the Mac it appears when you hold down the alt key.
The document window becomes small (it behaves like a navigation window) and a monitor window is created (it fills most of the screen). The monitor tool is selected and the cursor looks like a round sight.
Select a region into the small window and it will be displayed inside the large one.
It's the monitor tool that performs this action. If the monitor is not the current tool, you can obtain the same effect by selecting a region and pressing “m” on the keyboard.
You can do nothing directly into the monitor. Press 5 to swap the roles between the two windows: now you can manipulate the expanded region, for example you can integrate it. Press 5 again to swap the roles back.
You can resize both windows, if you like. The command Full + Monitor is only a shortcut to arrange the two windows in a certain way. You can get the same effect with the generic command Tools > Monitor, which does not resize the main window.
To return to the normality, close the monitor window and resize the navigation window.