When the IsOS function is given OS_TABLETPC as its dwOS argument, its answer is obtained by different methods in different SHLWAPI versions.

In the SHLWAPI version 6.0 from Windows Vista, and higher, the function returns TRUE if the following are both true:

In earlier builds, the function simply evaluates the system metric SM_TABLETPC (not caring whether this returns a result other than TRUE or FALSE).


The OS_TABLETPC case of the SHLWAPI function IsOS is supported in version 6.0 from Windows XP SP1, and higher. The Windows Vista SDK dated 2007 documents only the earlier implementation.