XmTabStackSelectTab(3) on Linux
The text c404918655d9, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A TabStack function that sets the currently displayed child "XmTabStackSelecttab" "TabStack functions" "XmTabStackSelectTab"