XmTextFieldSetAddMode(3) on Linux
The text bb391ae12b4b, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A TextField function that sets the state of Add mode "XmTextFieldSetAddMode" "TextField functions" "XmTextFieldSetAddMode"