x-register-dnd-atom
x-register-dnd-atom is a built-in function in `C source code
'.
(x-register-dnd-atom ATOM &optional FRAME)
Request that dnd events are made for ClientMessages with ATOM.
ATOM can be a symbol or a string. The ATOM is interned on the display that
FRAME is on. If FRAME is nil, the selected frame is used.