/usr/share/doc/libsx-dev/html/ is in libsx-dev 2.05-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/doc/libsx-dev/html/button.html
/usr/share/doc/libsx-dev/html/color.html
/usr/share/doc/libsx-dev/html/draw_area.html
/usr/share/doc/libsx-dev/html/drawing.html
/usr/share/doc/libsx-dev/html/font.html
/usr/share/doc/libsx-dev/html/form.html
/usr/share/doc/libsx-dev/html/functions.html
/usr/share/doc/libsx-dev/html/general.libsx.html
/usr/share/doc/libsx-dev/html/label.html
/usr/share/doc/libsx-dev/html/libsx.html
/usr/share/doc/libsx-dev/html/list.html
/usr/share/doc/libsx-dev/html/local.libsx.html
/usr/share/doc/libsx-dev/html/menu.html
/usr/share/doc/libsx-dev/html/misc.html
/usr/share/doc/libsx-dev/html/popups.html
/usr/share/doc/libsx-dev/html/scrollbar.html
/usr/share/doc/libsx-dev/html/string_entry.html
/usr/share/doc/libsx-dev/html/text_edit.html
/usr/share/doc/libsx-dev/html/toggle.html
/usr/share/doc/libsx-dev/html/windows.html