XmCreateCascadeButtonGadget(3) on Linux
The text f5644a7d1e0d, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
The CascadeButtonGadget creation function "XmCreateCascadeButton\%Gadget" "creation functions" "XmCreateCascadeButton\%Gadget"