You can try to read the registry key HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced\HideFileExt.

>Does anyone know how to programatically read the "Hide File Extension" option of Windows Explorer using a Windows API? I've been searching with no luck so far.
>
>I handle tech support calls fairly often that deal with a bug in Word 97 automation having to do with this setting, and I would like to programmatically check for this setting on app startup.