2 user_01
Во-первых, OnIncludeItem работает начиная с Windows 2000.
Во-вторых, Unfortunately, the dialog box always ignores your return value if the item has the SFGAO_FILESYSTEM and SFGAO_FILESYSANCESTOR attributes. In other words, if you're dealing with normal files and directories, or folders that are the parent of a file system folder (such as My Computer), by design the OFN_ENABLEINCLUDENOTIFY style doesn't apply. It works only with namespace extensions - так что наложить фильтр на обычные файлы увы не удастся