/usr/share/help/fr/gtkmm-tutorial/figures/keyboardevents_propagation.png is in gtkmm-documentation 3.18.0-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/help/fr/gtkmm-tutorial/figures/../../../C/gtkmm-tutorial/figures/keyboardevents_propagation.png