private void _OnPreviousSlideCommandCanExecute(object sender, CanExecuteRoutedEventArgs e)
{
if (!e.Handled)
{
e.CanExecute = PART_ZapScroller2.CanPrevious();
e.Handled = true;
}
}
private void _OnPreviousSlideCommandExecuted(object sender, RoutedEventArgs e)
{
PART_ZapScroller2.Previous();
PART_ZapScroller2.IsPlaying = false;
}