JavaScript Vertical Splitter
The JavaScript Vertical Splitter is a stand alone script that allows two side-by-side containers to be resized by dragging a handle left or right.
It can work in two different modes, the first allows you to resize by dragging and the second is a "click to show/hide".
To use the script you need the following...
And then you set it up using the following JavaScript.
VerticalSplitter.SetUpElement({ containerId: "resizeme", firstItemId: "first", secondItemId: "second" });