the position to determine the destination row for
the position to determine the destination row for
Return location for the path of the highlighted row, or NULL.
Return location for the drop position, or NULL
whether there is a row at the given position, TRUE if this is indeed the case.
Determines the destination row for a given position. drag_x and drag_y are expected to be in widget coordinates. This function is only meaningful if tree_view is realized. Therefore this function will always return FALSE if tree_view is not realized or does not have a model.