private void ApplicationBarIconButton_Click(object sender, EventArgs e)
{
this.ApplicationBar.IsVisible = false;
foreach (var b in this.ApplicationBar.Buttons)
{
((ApplicationBarIconButton)b).IsEnabled = false;
}
AddNewGroupViewModel vm = (AddNewGroupViewModel)this.DataContext;
vm.CreateNewGroup(this.GroupNameTextBox.Text, vm.SelectedMembers.ToList());
}
