XmMultiListUnselectAllItems(3) on Linux
The text 663abff2e420, 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 deselects all rows of the list "XmMultiListUnselectAllItems" "MultiList functions" "XmMultiListUnselectAllItems"