private void OnPresenterSessionItemSelected(object sender, PresentationItemEventArgs e)
            {
                AssertIsForeground();
                Contract.ThrowIfFalse(ReferenceEquals(this.PresenterSession, sender));

                SetModelSelectedItem(m => e.PresentationItem.IsSuggestionModeItem ? m.DefaultSuggestionModeItem : e.PresentationItem);
            }
            private void OnPresenterSessionItemCommitted(object sender, PresentationItemEventArgs e)
            {
                AssertIsForeground();
                Contract.ThrowIfFalse(ReferenceEquals(this.PresenterSession, sender));

                this.Controller.CommitItem(e.PresentationItem);
            }