private void MoveSlideUpButton_Click(object sender, RoutedEventArgs e)
        {
            if (SlideButtonsListBox.SelectedIndex > 0)
            {
                //UI
                ListBoxItem listBoxItem = SlideButtonsListBox.SelectedItem as ListBoxItem;

                int index = SlideButtonsListBox.SelectedIndex - 1;

                SlideButtonsListBox.Items.Remove(listBoxItem);
                SlideButtonsListBox.Items.Insert(index, listBoxItem);
                SlideButtonsListBox.SelectedIndex = index;
                SlideButtonsListBox.Focus();

                //Data
                Presentation.RemoveSlide(CurrentSlide);
                Presentation.InsertSlideAt(index, CurrentSlide);
            }
        }
        public void RemoveSlide()
        {
            if (Presentation.Slides.Count == 0)
            {
                return;
            }

            //Remove From Presentation
            Presentation.RemoveSlideAt(SlideButtonsListBox.SelectedIndex);

            //Remove UI
            ListBoxItem listBoxItem = SlideButtonsListBox.SelectedItem as ListBoxItem;

            SlideButtonsListBox.Items.Remove(listBoxItem);

            if (SlideButtonsListBox.Items.Count != 0)
            {
                SlideButtonsListBox.SelectedIndex = SlideButtonsListBox.Items.Count - 1;
            }

            SlideButtonsListBox.Focus();

            UpdateDisplay();
        }