XmTabListReplacePositions(3) on Linux
The text 049f8907877e, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A convenience function that creates a new tab list with replacement tabs "XmTabListReplacePositions"