XmContainerGetItemChildren(3) on Linux
The text dbdf6784f67f, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
Container widget function to find all children of an item "XmContainerGetItemChildren" "XmContainer"