gtk-drag-set-icon-gicon (context icon x y)

context -- a gdk-drag-context object for a drag, this must be called with a drag context for the source side of a drag
icon -- a g-icon object
x -- an integer with the x offset of the hotspot within the icon
y -- an integer with the y offset of the hotspot within the icon

Sets the icon for a given drag from the given icon. See the documentation for the gtk-drag-set-icon-name function for more details about using icons in drag and drop.