How to use the existing Png-Shell-Thumbnail for my file types?

I am currently writing an application working with specially prepared image data. Another tool prepares the images (basically PNGs with additional data stored in the meta-data section). Now my tool works with these files, but not with all PNGs, so "we" decided to use a different file extension. So far, so good.

Now, because I am a lazy sack I implemented some file type registration to allow double-clicking on the file and opening it in my application (no problem at all).

And here is my Question: It w开发者_如何学编程ould be cool if the windows explorer could still show me the thumbnail previews for my files. Since they basically are still PNG files, it should be possible without writing my own shell extension (at least I believe so).

I quickly tried to copy all registry keys and values from HKCR.png to HKCR.mInDat (my file name ext) and it worked. However, I would prefere knowning what I am doing ;-)

Which of the registry settings are responsible for the thumbnail preview control and which can I use to get the preview for my file types?

I tried to google it, but I failed, since it seems I am unable to come up with the right buzz-words to find the info I need. Please, help me.

Thank you!

Yours, 3of4

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Simple:

[HKEY_CLASSES_ROOT\.apng]
@="apng"
"Content Type"="image/png"
"PerceivedType"="image"

[HKEY_CLASSES_ROOT\apng\shellex\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{3F30C968-480A-4C6C-862D-EFC0897BB84B}"