A short-cut or hotkey to go back to last view.
For example, I'm previewing a route and notice's that the shaping point is not on an intersection but a business nearby (in zumo this can be a problem with flags on its display or audible announcements). With the zoom function, I can enlarge the map around the intersection, put a new shaping point on the intersection and erase the erroneous shaping point. However, going back to the previous view (pre- zoom in) requires a lot of fiddling and readjusting to go back to where where I was previously. A simple function key such as ‘Ctrl+L’ for last view would save a TREMENDOUS amount of time.
I have such a key on a CAD program and for moving between a broad view and detail view its irreplaceable.
