Heya,
First of all, I'm not sure this was done by paint.net! But in my Registry, it is set as the dds default application ("Computer\HKEY_CLASSES_ROOT\.dds"), and the dds MimeType is set to "image/vnd.ms-dds". Which is wrong however, the correct MimeType is "image/vnd-ms.dds" (switched dash/dot). See https://msdn.microsoft.com/en-us/library/windows/desktop/dn424129(v=vs.85).aspx
Again, I'm not sure it was written there by paint.NET, but it's incredibly hard to find out where it might've come from, and p.N seems to be the most likely culprit at this point.
Would be awesome if someone with access to the source could take the time to check the installer… Thanks!
PS: Why I found this? Don't ask… xP
