The accessor functions
drop-object-pane-y return the x and y coordinates within the pane that the object is being dropped over. This information is only meaningful when the pane is an instance of output-pane or one of its subclasses.
drop-object-pane-y should only be called within a
. They are not supported on X11/Motif. See simple-pane for information about drop callbacks.
CAPI User Guide and Reference Manual (Windows version) - 3 Aug 2017