Introduction
Dialog box control management is a perpetual problem. You want to have certain
controls enabled or disabled, visible or invisible, based on the values of other
controls. Unlike windows, there is no ON_UPDATE_COMMAND_UI mechanism
for doing this. Most books that show examples of how to do it get it wrong. That's
because most of them illustrate fairly simple examples, where the simple methods
are easy to write and easy to maintain. Unfortunately, in the real world, dialog
boxes are usually fairly complex, and the enabling conditions are nontrivial.
The simple methods illustrated in the introductory textbooks are considerably
less than adequate in this case. A decade of Windows programming has allowed
me to develop a methodology for handling this.