XmIconBoxIsCellEmpty(3) on Linux
The text a9bed16275ad, as Debian 13 (Trixie), Debian 12 (Bookworm), Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
A function that determines whether a cell in the IconBox is empty "XmIconBoxIsCellEmpty" "IconBox functions" "XmIconBoxIsCellEmpty"