I ran into an issue in our project with animations. I was trying to create a panel that can fade In/Out in the middle of the other animation, interrupting the Fade In for the Fade Out, or the other way around, starting the animation with the current opacity value (only using "To", not "From"). I created a custom animation extending from DoubleAnimation in our Blend project, to solve the issue with the duration of those animations having always the same duration with less value difference, and changed it to have constant speed or delta, so the animation feels the same with any starting opacity value.

The problem is that it is not supported on C#/Unity, as I was being told in the forums by jsantos, after I tried the code and Found that there's no way to extend any base or defined animation class in the Noesis package. So for the moment I have to approach the issue adjusting the design a bit.

Here's a simple snippet of the class that works as intented on Blend.

using System;
using System.Windows;
using System.Windows.Media.Animation;

public class DoubleFixedSpeedAnimation : DoubleAnimation {

    public static readonly DependencyProperty ValuePerSecondProperty = DependencyProperty.Register("ValuePerSecond", typeof(double), typeof(DoubleFixedSpeedAnimation));

    public double ValuePerSecond {
        get { return (double)GetValue(ValuePerSecondProperty); }
        set { SetValue(ValuePerSecondProperty, value); }
    }
    protected override Freezable CreateInstanceCore() {
        return new DoubleFixedSpeedAnimation();
    }
    protected override double GetCurrentValueCore(double defaultOriginValue, double defaultDestinationValue, AnimationClock animationClock) {
        double destinationValue = To ?? defaultDestinationValue;
        double originValue = From ?? defaultOriginValue;
        double value = originValue + ValuePerSecond * animationClock.CurrentTime.Value.TotalSeconds;            
        return ValuePerSecond > 0 ? Math.Min(destinationValue, value) : Math.Max(destinationValue, value);
    }
}