fltk backend and undefined gluOrtho2D

[Alexander Barth]

Hi all,
I try to compile a recent checkout of octave (from
http://www.octave.org/hg/octave). The compilation fails at:

./DLD-FUNCTIONS/fltk_backend.cc: In member function ‘virtual void
OpenGL_fltk::draw_overlay()’:
./DLD-FUNCTIONS/fltk_backend.cc:145: error: ‘gluOrtho2D’ was not
declared in this scope

I have fltk version 1.1.7. Is this version recent enough? On my system
gluOrtho2D is declared in /usr/include/GL/glu.h but this file is not
included in fltk_backend.cc.

Any help would be greatly appreciated!
Cheers,
Alex