I made a lot of changed on this object,such as *
// 1.Encapsulates all code in one userobjet,since PB does not *
// support "Address of Function" , so we can not set new *
// WndProc, just makes the object more easy to use. *
// 2.Uses structure array instead of Datastore *
// 3.Calc width of menuitem at runtime(MEASUREITEM) *
// 4.Draw disabled status
