gtk_tree_view_get_path_at_pos() and gtk_tree_view_get_dest_row_at_pos() fails with a GtkWarning if bin_window is NULL:

    GtkWarning: gtk_tree_view_get_path_at_pos: assertion `tree_view->priv->bin_window != NULL' failed

That's not entirely wrong since the functions doesn't work if the GtkTreeView isn't realized. But the warnings aren't needed, instead of failing with:

    g_return_val_if_fail (tree_view->priv->bin_window != NULL, FALSE);

The could could just check if there is a bin_window and return FALSE if not:

    if (!tree_view->priv->bin_window)
        return FALSE;

That would be more consistent with how the model attribute is checked for.