title: Session Timeout Warning in ASP.NET
body: <p>I have an asp.net site that I need to have a popup/layer/alert happen when the session reaches its timeout (lets say 10 minutes).  The popup will say that your account session will exprire due to inactivity and have a button for continue session or a button for logout.</p>
  
  <p>I see different ways to do this online, but what's the best/proper way to handle this?  Do I have to put an additional timeout if the popup is open too long?</p>