Thanks for the link Brendan [*].
In the end I managed to find the problem with my code so I will be using my patched Blender as my viewer for the time being. At some point I may look at the problem again. It may be an issue with my fltk library.
I don't know if it's a bug of if it's intended to fail with tiled-images.
[*] I actually had some linking problems with your Xcode solution (I don't have cg here, and didn't want to get it), and in the end it made more sense for me to look deeper in my problem instead of wasting time with linking issues.
Regards,
Dalai