XmMultiListToggleRow(3) on Linux
The text f50f512c9926, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
An MultiList function that toggles the selection state of a specified row "XmMultiListToggleRow" "Extended List functions" "XmMultiListToggleRow"