Dialogs have always been a hobgoblin in the Windows platform. Developers are constantly faced with an unacceptable choice. One option is to use the built-in dialog and pretend Ok/Cancel or Yes/No are really appropriate prompts for the user. The other is to create their own dialog from scratch, which seems like a waste of time for what should be a simple prompt.
Windows Vista addressed this with the Task Dialog. This dialog provides a framework that covers most dialog scenarios while maintaining consistency across applications. But it also introduces a new problem in that it is not backwards compatible with Windows XP.
Hedley Muscroft tackled this problem by creating a wrapper/emulator for the Task Dialog. When running on Windows XP, the application will use his hand-rolled clone which supports most of the Task Dialog functionality. On Vista, it automatically switches to the built-in dialog.