If a range is flippable, it will switch its direction if it is horizontal and its direction is %GTK_TEXT_DIR_RTL.
See gtk_widget_get_direction().
%TRUE to make the range flippable
2.18
See Implementation
If a range is flippable, it will switch its direction if it is horizontal and its direction is %GTK_TEXT_DIR_RTL.
See gtk_widget_get_direction().