A better way to resize these boxes?

[rpflo]

Here's what I'm talking about:

http://ryanflorence.com/sandbox/mootools/slideResize/

I've got 3 boxes stacked horizontally and two Sliders.  I used the
sliders to resize a box, and adjust the others accordingly.

Is there a better way to do this with Drag or Drag.Move?

I need the handles to only move horizontally and also accommodate
changing the window size.  makeResizable allows the thing to be
resized both horizontally and vertically.

Maybe this is the way to do it?

Thanks :)