If you're using overflow:hidden in the html, body and form elements when designing you page, be careful because these might affect your RadWindow. RadWindows uses an IFRAME to display page-content and hence another set of html, body and form-tags. In our case we had overflow:hidden for design purposes which carried over causing scollbars to not show in the RadWindows. We solved this by placing the overflow-part in the masterpage itself and not the theme.
Just a tip :)
Just a tip :)