/usr/share/doc/libfltk1.3-dev/README.gz is in libfltk1.3-dev 1.3.0-5build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libfltk1.3-dev/../libfltk1.3/README.gz
/usr/share/doc/libfltk1.3-dev/../libfltk1.3/README.gz