WPF DataGrid选中改变时，还原选中行

if (index != dataGrid1.SelectedIndex && System.Windows.Forms.MessageBox.Show("1", "", System.Windows.Forms.MessageBoxButtons.OKCancel) == System.Windows.Forms.DialogResult.Cancel)
{
    Dispatcher.BeginInvoke(System.Windows.Threading.DispatcherPriority.Loaded, new Action(() =>
    {
    	dataGrid1.SelectionChanged -= dataGrid1_SelectionChanged;
        dataGrid1.SelectedIndex = index;
        dataGrid1.SelectedItem = dataGrid1.Items[index];
        dataGrid1.CurrentItem = dataGrid1.Items[index];
    	dataGrid1.SelectionChanged += dataGrid1_SelectionChanged;
    }));

    return;
}

index = dataGrid1.SelectedIndex;