private void ShowNewCampaignWindow(object sender, RoutedEventArgs e)
        {
            var manager = GameSystemManager.GetNewCampaign();

            var newCampaignWindow = new CampaignWindow(manager);
            newCampaignWindow.Show();
        }
        private void ShowExistingCampaignWindow(object sender, MouseButtonEventArgs e)
        {
            var grid = (DataGrid)sender;

            if (grid.SelectedIndex == -1)
            {
                return;
            }

            var campaignManager = (CampaignManager)grid.SelectedItem;

            var campaignWindow = new CampaignWindow(campaignManager);
            campaignWindow.Show();
        }