XmScrolledWindowSetAreas(3) on Linux
The text 026ee31db2ff, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A ScrolledWindow function that adds or changes a window work region and a horizontal or vertical ScrollBar widget to the ScrolledWindow widget "XmScrolledWindowSetAreas" "ScrolledWindow functions" "XmScrolledWindowSetAreas"