FWIW, I didn't really like the idea of using the Tag property.
Initially it looked like a quick-fix, but an unnecessary one. Having
selected a dropdown item, surely there's a way of capturing that
selection without having to double-handle the value by entering it in
the XML as a Tag property.

My dropdowns are populated by values in cell ranges so, given that the
dropdown captures the selection's index (base 0), I can use index + 1
as the pointer to the cell in the range. Hopefully that might assist
someone who is searching for a solution to my problem.

Paul