appends row, jumps to it and allows user to input name

def on_category_add_clicked(self, button):
        """ appends row, jumps to it and allows user to input name """

        new_category = self.category_store.insert_before(self.category_store.unsorted_category,
                                                         [-2, _("New category")])

        model = self.category_tree.get_model()

        self.categoryCell.set_property("editable", True)
        self.category_tree.set_cursor_on_cell(model.get_path(new_category),
                                         focus_column = self.category_tree.get_column(0),
                                         focus_cell = None,
                                         start_editing = True)