Comment 4 for bug 987641

Ok, according to to the manual for the GIO library that GDK uses to decide on file type when GDK_PIXBUF_USE_GIO_MIME is enabled (http://developer.gnome.org/gio/2.26/gio-GContentType.html#gio-GContentType.synopsis), has a platform-dependent way of doing it. So it could vary depending on platforms even with the same flags.

But wait, there's more! I did the obvious thing and checked if Eye Of Gnome could open the file, and it could. Since it should be using the same GDK, that's curious. It could possibly be a bug in gdk-sharp, the GDK binding we use.

If I open a terminal and run "file --mime-type test1.tga" it returns application/octet-stream instead of the expected (in GDK) image/x-tga, while pngs and jpegs get image/png and image/jpeg. There could be something there as well.

Lots of possible reasons so far! :P