/// <summary>Destroys this RDP.</summary>
 public void Destroy()
 {
     // Destroy it:
     if (Renderer != null)
     {
         Renderer.Destroy();
         Renderer = null;
     }
 }
        internal override void NowOffScreen()
        {
            if (Renderer != null)
            {
                FlatWorldUI fwui = Renderer;
                Renderer = null;

                // Make sure we're on the main thread:
                Callback.MainThread(delegate(){
                    // Destroy it:
                    fwui.Destroy();
                });
            }
        }