drag and drop under Mac not using dnd-protocol-alist?

[emacs user]

hi all, it seems that the drag-and-drop operations under mac do not
use the dnd.el mechanism, in particular dnd-protocol-alist.  as a
result, there is incompatibility with the operation on other systems.
for example, the new support for attachments using dnd in VM seems not
to work under mac.  does anyone know how to make the mac dnd be
compatible with the normal emacs behavior?  cheers, E