display small modal window on browsers
<p>I use VS2010,C# to develop ASP.NET web app, recently I've seen some sites that display a small window (it is somehow modal) displaying on top of screen, and while it is displayed the whole screen is somehow dimmed (like having a gray alpha layer), so that user can do nothing on the main screen and focus is only on the small window.</p>

<p>An example can be found here:</p>

<p><a href="http://www.geda.de/Permanentanlagen/Industrieaufzuege/Materialaufzuege" rel="nofollow">http://www.geda.de/Permanentanlagen/Industrieaufzuege/Materialaufzuege</a>, </p>

<p>you can click on images to see the window. I've heard that this technique is used in facebook also</p>

<p>how can I achieve this effect? I think it is javascript, right? can I design this small window in VS and using toolbox? how can I display it and disable other elements? how to render an alpha layer on top of screen? is there any tips or samples?</p>

<p>I'm searching for a cross-browser solution</p>
