Asks the GtkTreeDragDest to insert a row before the path dest, deriving the contents of the row from selection_data. If dest is outside the tree so that inserting before it is impossible, FALSE will be returned. Also, FALSE may be returned if the new row is not created for some model-specific reason. Should robustly handle a dest no longer found in the model!
Determines whether a drop is possible before the given dest_path, at the same depth as dest_path. i.e., can we drop the data in selection_data at that location. dest_path does not have to exist; the return value will almost certainly be FALSE if the parent of dest_path doesn't exist, though.
the main Gtk struct
GTK+ supports Drag-and-Drop in tree views with a high-level and a low-level API.
The low-level API consists of the GTK+ DND API, augmented by some treeview utility functions: gtk_tree_view_set_drag_dest_row(), gtk_tree_view_get_drag_dest_row(), gtk_tree_view_get_dest_row_at_pos(), gtk_tree_view_create_row_drag_icon(), gtk_tree_set_row_drag_data() and gtk_tree_get_row_drag_data(). This API leaves a lot of flexibility, but nothing is done automatically, and implementing advanced features like hover-to-open-rows or autoscrolling on top of this API is a lot of work.
On the other hand, if you write to the high-level API, then all the bookkeeping of rows is done for you, as well as things like hover-to-open and auto-scroll, but your models have to implement the GtkTreeDragSource and GtkTreeDragDest interfaces.