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Comix displays only the first page of a multi-page TIFF (I cannot refer you to a valid sample  but you can create one using tiffcp).
 <URL: http://bugzilla.maptools.org/show_bug.cgi?id=2298 >
GDK (and in extension, Comix) does not support loading multi-image TIFF files. This would also require a redesign of Comix' page handling (the assumption of one file being one page is scattered over many places).
Did I mention yet that herrekberg, the programmer of Comix, has been missing since 2009?
If someone was interested in working on this they might be able to be able to make use of the support for Multipage TIFF in the Python Imaging Library (PIL).
PIL considers both multipage TIFF and GIF as "Image Sequences"
The patches to add GIF support might even be a useful example, and starting point for similar work on TIFF