I have written a shell extension library (to extract music file attributes from .m4a files) which implements only the following four "new" Vista shell extension interfaces: IThumbnailProvider IPropertyStore IPropertyStoreCapabilities IInitializeWithStream I have registered the dll using the following registry entries: [HKEY_CLASSES_ROOT\.m4a\ShellEx\{E357FCCD-A995-4576-B01F-234630154E96}] @="{9C04FB4E-95BD-477F-BB57-64AD0E16D116}" [HKEY_CLASSES_ROOT\CLSID\{9C04FB4E-95BD-477F-BB57-64AD0E16D116}] @="MP4 Property Handler (by Andrew Fiddian-Green)" [HKEY_CLASSES_ROOT\CLSID\{9C04FB4E-95BD-477F-BB57-64AD0E16D116}\InprocServer32] @="C:\\DEVELO~1\\MP4\\MP4SHE~1.DLL" "ThreadingModel"="Apartment" [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\PropertySystem\PropertyHandlers\.m4a] @="{9C04FB4E-95BD-477F-BB57-64AD0E16D116}" [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions\Approved] "{9C04FB4E-95BD-477F-BB57-64AD0E16D116}"="MP4 Property Handler (by Andrew Fiddian-Green)" When I open Windows Explorer, it correctly calls the methods of IInitializeWithStream, IPropertyStore and IPropertyStoreCapabilities and it displays the respective properties perfectly in the columns of the Explorer details view. But when I switch to Explorer's Icons view, Explorer does NOT call the method of IThumbnailProvider; instead Explorer continues to display the small icon extracted from the file associated application (in this case iTunes). I have tried lots of things without success and now I am at a total loss how to solve it. I can only think of two possible errors: 1) Is there is something wrong with or missing from the above registry entries? 2) Do I need to implement other Interfaces in addition to IThumbnailProvider, IPropertyStore, IPropertyStoreCapabilities and IInitializeWithStream? (For example some of the "old" property shell interfaces from Windows XP?) Any help would be much appreciated. Regards, AndrewFG
