DragResize script just uses NGUIMath.ResizeWidget, which doesn't have a "max" parameter. Only "min". Easiest way to limit something's side is to do it inside UIDragResize's OnDrag function, just before passing the values to NGUIMath.ResizeWidget, or to just do your own logic after the resize operation -- is the widget's size bigger than some value? If so, just set it to that value.
