What is the purpose of Lock Scale?
To lock the scale, so that only zoom and center changes are allowed. When on, resizing the Map Window does not change the scale of the content. When off, resizing the Map Window resizes the map content, so that everything remains in view.
When is Lock Scale active?
When a Map window is active.
How do I access Lock Scale?
On the MAP tab, in the Options group, click Lock Scale.