Silverlight 4: ChildWindow freezes the entire application

There is a known bug in Silverlight 4 ChildWindow control:
sometimes, without apparently reason, application freezes and you need to refresh the page.

A easy solution for this issue is this to use this instead of normal ChildWindow:

public class MyChildWindow : ChildWindow
{
      protected override void OnClosed(EventArgs e)
      {
           base.OnClosed(e);
           Application.Current.RootVisual.SetValue(IsEnabledProperty, true);
      }
}