/// <summary>
        /// Event is raised when rename Viewpoint is clicked from the grid.
        /// </summary>
        /// <param name="sender">Ribbon control</param>
        /// <param name="e">Routed event</param>
        private void OnRenameViewpointEvent(object sender, EventArgs e)
        {
            var viewModel = sender as ViewpointViewModel;
            if (viewModel != null)
            {
                CaptureViewpoint dialog = new CaptureViewpoint();
                System.Windows.Interop.WindowInteropHelper helper = new System.Windows.Interop.WindowInteropHelper(dialog);
                helper.Owner = (IntPtr)ThisAddIn.ExcelApplication.Hwnd;

                viewModel.RequestClose += new EventHandler(dialog.OnRequestClose);
                dialog.DataContext = viewModel;
                dialog.UpdateLayout();

                dialog.ShowDialog();

                if (dialog.DialogResult.HasValue && dialog.DialogResult.Value)
                {
                    if (!string.IsNullOrWhiteSpace(viewModel.Name))
                    {
                        viewModel.CurrentPerspective.Name = viewModel.Name;
                        SaveViewpointMap(ThisAddIn.ExcelApplication.ActiveWorkbook);
                        this.ribbonInstance.BuildViewpointMenu(this.currentViewpointMap.SerializablePerspective);
                    }
                }

                viewModel.RequestClose -= new EventHandler(dialog.OnRequestClose);
                dialog.Close();
            }
        }