TreeDragSource data_get location

[Kevin Ryde <user42 zip com au>]

I'm tinkering with a DRAG_DATA_GET in a custom treemodel implementing
TreeDragSource and though to fill the Gtk2::SelectionData using one of
my sub-objects (or it if possible, and myself if not).

Could the drag_data_get method take a selectiondata object which to
write to, instead of always making a new one?  Per below, umm err tested
only a little bit.

Attachment: GtkTreeDnd.xs.drag_data_get.diff
Description: Text Data