title: jQuery/CSS: fixed overlay should not allow scrolling of background?
body: <p>i have a overlay box that is fixed and centered on the screen. The page itself is rather long and has a vertical scrollbar.</p>
  
  <p>I'd like to disable scrolling of the page itself once the overlay is shown. However I can't disable scroll completely because some overlays do have <code>overflow-y:scroll</code> for themselves. So the content in the overlay should be scrolled but the page itself should be stuck.</p>
  
  <p>Any idea how to solve that with jquery or css?</p>