Could you point me to a link on this behavior? I'm pretty sure that many of these buttons send a signal that applications can hook into and override the default (do-nothing) behavior.
The documentation for those specific values appears to be non-existent - the latest (as far as I'm aware) HTML Help documentation can be found here:
http://www.microsoft.com/download/en/details.aspx?id=21138
Additionally, as Francois mentioned, the HTML Help header files do include some references to unimplemented functionality.