>The same can be done programmatically; there is a hierarchy of registry keys created under HKEY_CLASSES_ROOT to accomplish the by the Windows Explorer. You can look at this using REGEDIT to explore the keys associated with your file type; if you've associated the extension "foo", then the entry in the registry would be under HKEY_CLASSES_ROOT\.foo
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>Be aware that this may point to another entry, in which case the additional entry and its sub-trees will be needed as well. You can use the FFC registry class, or one of the down;loadable registry classes from here on UT to make the necessary changes.
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>No, I do not have source code to give you to do this.

In a recent quest to do this myself programmatically, I was surprised to find out that there is not a windows function (that I could find) that creates these entries for you. Searching in MSDN only turns up instructions on how to create the registry entries manually. Hmph. I guess I'll turn the code that I wrote to do it into a reusable class and upload it. One of these days.

Imagine if we had to register our COM objects by hand? What a pain.

One should be aware that with Active desktop, there are now two levels of file associations that Explorer uses to view a file. The one that runs when you double-click the file is the default verb found under the file's classid in the lower half of HKEY_CLASSES_ROOT, (This is found under MyFile\Shell\Open\Command) and the one that Explorer uses to preview the file, if it is a previewable file. This one is found in the top half of HKEY_CLASSES_ROOT under the files extension, as the name of a subfolder whose name is the GUID of a thumbnail extractor program. In my experience, these entries almost always point to the same file: a thumbvw.dll.