/usr/share/man/man3/mouse_w.3alleg4.gz is in allegro4-doc 2:4.4.2-5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man3/mouse_x.3alleg4.gz
/usr/share/man/man3/mouse_x.3alleg4.gz