Make content 100% height with scrollbar

I am using CKEditor (http://ckeditor.com) and I've created my own custom file browser...

Problem is, when you open the filebrowser, it opens it in a new popup window and has no scrollbars. I submitte开发者_如何学Cd a support ticket 2 weeks ago to find out how to add the scrollbars and no answer. I can't find what to edit in the code either...

So what I plan to do is make it scroll using CSS...

I found this post about making the body 100% (Border around 100% body height and width (HTML 4.01 Strict)) but it doesn't add scrollbars.

Any ideas how I can force scrollbars using CSS?

On elements with fixed height/width, this should add scrollbars:

overflow:auto;

http://www.w3.org/TR/CSS21/visufx.html#overflow

http://www.w3schools.com/Css/pr_pos_overflow.asp