Thanks, mjlecomte. I think I've got it nearly formatted the way I want now.
Another question for the forum, however. In looking at several examples found elsewhere, I'm having some trouble determining how to manipulate the CheckboxSelectionModel so that certain boxes render as checked on load. In my object (seen way back in the first post), each of my 'categories' has both a name and a boolean 'enabled' value. Ideally, that value would be used to determine the checked status of each of the categories when they display.
Most of the examples I've found so far seem to be based on situations where all the boxes start as unchecked, and my attempts thus far to do something as simple as start with all of the boxes checked have returned error: "this.grid.store is null or not an object".
Can anyone point me to an example where the CheckboxSelectionModel is used in a GridPanel to render certain boxes as checked on load? My forum searches haven't turned anything up yet.