Comment text in shape sheet

[myVisio]

1. I think it will be a good idea if the developer of Visio solution can enter comment for new defined cells in the user section, sometimes it is hard to remember the role of a cell the developer created months ago (without looking outside of the shape sheet).

[Paul Herber]

Isn't the row name or the prompt section adequate? If you look at, say, the org chart shapes the user defined cells are mostly named such that you see what they are supposed to be used for.
There's certainly no text area that can be used to explain any complicated formulae.