XmMultiListGetSelectedRows(3) on Linux
The text 304686de2d95, 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 returns the rows that currently are selected. "XmMultiListGetSelectedRows" "List functions" "XmMultiListGetSelectedRows"