/usr/share/man/man3/setCDKButtonboxURChar.3.gz is in libcdk5-dev 5.0.20060507-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man3/cdk_buttonbox.3.gz
/usr/share/man/man3/cdk_buttonbox.3.gz