public void Close()
 {
     if (Controller.PresentationManager.CurrentPresentation != presentation)
     {
         presentation.Close();
     }
 }
        void pres_OnFinishedLoading(object sender, EventArgs args)
        {
            finishedLoading  = true;
            recoverSelection = null;
            if (this.SlideListBox.SelectedIndex >= 0)
            {
                presentation.CurrentSlideIndex = this.SlideListBox.SelectedIndex;

                if (Controller.PresentationManager.CurrentPresentation != oldPresentation && oldPresentation != null)
                {
                    oldPresentation.Close();
                }
                Controller.PresentationManager.CurrentPresentation = presentation;

                oldPresentation = null;
            }
        }