Function fltk_sys::tree::Fl_Tree_extend_selection_dir

pub unsafe extern "C" fn Fl_Tree_extend_selection_dir(
    self_: *mut Fl_Tree,
    from: *mut Fl_Tree_Item,
    to: *mut Fl_Tree_Item,
    dir: c_int,
    val: c_int,
    visible: c_int
) -> c_int