Command line: AFZOOM
Ribbonbar: ProSig EPU -> Tools -> Display -> Zoom Window
The function 'Zoom Window' makes it possible to set up a zoom section in one window and perform the actual zoom in another window. This function is only useful if you have more than one window open.
The function first scans the lower left corner, then the upper right corner of the zoom section. If you choose not to pick a point and just click enter/return instead, the function selects the corresponding corner of the window as the corner of the zoom section.
All you need to do then is double-click on the window that you want to zoom in on.