private void btnBrowse_Click(object sender, RoutedEventArgs e)
 {
     var dialog = new PeopleSelectorDialog();
     var u = (UserInfoParam)DataContext;
     dialog.DataContext = u;
     dialog.ShowExisting = false;
     dialog.Show();
 }
 private void txtError_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
 {
     var dialog = new PeopleSelectorDialog();
     var u = (UserInfoParam)DataContext;
     dialog.DataContext = u;
     dialog.ShowExisting = true;
     dialog.Show();
 }