XmCreateLabelGadget(3) on Linux
The text 4ea1ee00d5b2, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
The LabelGadget creation function "XmCreateLabelGadget" "creation functions" "XmCreateLabelGadget"