gboolean drag_data_delete ( GtkTreeDragSource* drag_source, GtkTreePath* path )
GtkTreeDragSource to delete the row at
it was moved somewhere else via drag-and-drop. Returns
if the deletion fails because
path no longer exists, or for
some model-specific reason. Should robustly handle a
longer found in the model!
Row that was being dragged.
The data is owned by the caller of the function.