Create a new collection (or open an existing one).
In the User Environment, select the collection. In the Inspector, make sure that the Canvas view is showing.
Right-click on the Collection's icon from the Inspector's title bar. In the drop-down menu that appears, navigate to the "Grids >" item
Note that all grid options appear to be selected, but none can actually be selected.
(The same happens for regular Inspectors outside of the User Environment, but not in the Center Panel. There is no drop-down available from the Panel Inspector.)