XmListDeselectPos(3) on Linux
The text 207c9cf20814, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A List function that deselects an item at a specified position in the list "XmListDeselectPos" "List functions" "XmListDeselectPos"