In a recent discussion with eNjoy (yep, there should be some media player and I'm hoping it will be usable soon) developer, I found that Ubuntu does not installs FLTK correctly or at least packager missed few important things.
FLTK keeps header names under .H extension; I'm not sure why
is this, maybe legacy stuff or due some strange platforms that
likes C++ header files ending with .H and source files ending with
.C (FLTK uses .cxx here). And since everyone expects .h extension
for headers no matter used C or C++, FLTK plays fair here too:
installation procedure will create .h symbolic links to those .H
files (I'm aware of attempt from C++ purists to keep C++ headers
under .hpp extension or no extension at all, like headers from STL,
but I'm finding this practice little bit disgusting).
Now, as you guessed, I used .h for FLTK normally as for any
other header file all over the code (edelib and ede 2.0), not
thinking that some packager will mess things up. Maybe they see
this as perfectly normal, but shouldn't distro package resemble the
make install" or whatever
So, latest revisions of edelib and ede2 modules have fixed
issue". Hopefully, things
are less distro dependent now, but, as usually, you never know...