# File lib/rubygame/rect.rb, line 581
        def union!(rect)
                self.normalize!
    rleft, rtop = self.topleft
    rright, rbottom = self.bottomright
                r2 = Rect.new_from_object(rect).normalize!

                rleft = [rleft, r2.left].min
                rtop = [rtop, r2.top].min
                rright = [rright, r2.right].max
                rbottom = [rbottom, r2.bottom].max

                self[0,4] = rleft, rtop, rright - rleft, rbottom - rtop
                return self
        end