Ah, those are good reasons to stick with Dashboard, then.
Unfortunately, without calculating a separate field for "first letter of name", you wouldn't be able to even do the unique letter, as category selectors only operate on "equals" and "not equals". I suppose you could use a Data Expression instead of the layer itself, but that seems like a lot of work...
What we really need is a new kind of selector that can utilize "begins with" / "contains" / "ends with".
- Josh Carlson
Kendall County GIS