Drag and zoom

Here is the example fla.

What I want to drag the button towards right ( upto the end of the line on the right side) and the box will be zoomed in ( centre) and when I dragged the button towards left ( upto the end of the line on the left side) the box will zoom out ( centre).

How can I do that. Any help or any tute help will be highly appreciated.

trnghosh