title: Dismissing UIAlertViews when entering background state
body: <p>Apple recommends dismissing any <code>UIAlertViews/UIActionSheets</code> when entering background state in iOS 4. This is to avoid any confusion on the user's part when he relaunches the application later. I wonder how I could elegantly dismiss all UIAlertViews at once, without retaining a reference to it everytime I set one up...</p>
  
  <p>Any idea ?</p>