In it, the return of OnCommand is ignored. And the message is passed to OnMessageReflect regrdless of the fact it was already handled. CWnd::WndProcDefault does not ignore it. Is this on purpose or slipped through? Btw, CPropertySheet::WndProcDefault also ignores the result of OnCommand
In pratical terms this doesn't make much difference, but honouring the return value of OnCommand is preferred. I'll make the appropriate change to CDialog and CPropertySheet in the next official release.