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!
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!