private void AnimateTabOpening_Width()
{
root.Opacity = 1;
var animation = new DoubleAnimation();
animation.From = START_WIDTH;
animation.To = MaxWidth;
animation.Duration = new Duration(TimeSpan.FromMilliseconds(TAB_OPENING_WIDTH_ANIMATION_TIME));
animation.Completed += Opening_WIDTH_Completed;
var ease = new CubicEase();
ease.EasingMode = EasingMode.EaseIn;
animation.EasingFunction = ease;
root.BeginAnimation(MaxWidthProperty, animation);
}