Click the button to open a modal dialog window. When you do so, scrollbars will appear in the browser window even though they are not necessary. They appear to be caused by an over-sized overlay DIV that is created by the dialog component of jQuery UI.
This is a pretty simple test case. One possible area of concern: I'm not using an official jQuery UI Theme. I'm using a small subset of the CSS classes in a Theme, so perhaps I've broken something there.
You should see scrollbars on the browser window now.