//Show circular Progressing Indicator
private void ShowProgressBar()
{
DoubleAnimation fadeOut = Animations.FadeOut;
fadeOut.Completed += delegate {
OkButton.Visibility = Visibility.Collapsed;
CircularProgressBar.Visibility = Visibility.Visible;
CircularProgressBar.BeginAnimation(OpacityProperty, Animations.FadeIn);
};
OkButton.BeginAnimation(OpacityProperty, fadeOut);
}