How can I pause a storyboard?

This seems like it should be a no-brainer, but I can't get a WPF storyboard to pause. I call Pause and nothing happens -- it keeps right on animating.

Here's a repro case: a button that animates its width. If you click the button, it calls Pause on the storyboard. I would expect that, as soon as I click the button, its width should stop changing; instead its width keeps right on animating as if I never called Pause.

NameScope.SetNameScope(this, new NameScope());
var storyboard = new Storyboard();

var button = new Button { Content = "Pause", Name = "pause" };
this.Content = button;
RegisterName(button.Name, button);
var animation = new DoubleAnimation(0, 200, TimeSpan.FromSeconds(5));
Storyboard.SetTargetName(animation, button.Name);
Storyboard.SetTargetProperty(animation,
    new PropertyPath(FrameworkElement.WidthProperty));
storyboard.Children.Add(animation);

button.Click += (sender, e) => { storyboard.Pause(this); };
storyboard.Begin(this);

From what I understand of the docs, I should call the Pause(FrameworkElement) overload with the same parameter I passed to Begin, hence the Pause(this) above. But I've also tried storyboard.Pause(), with no 开发者_高级运维change in behavior. I also tried storyboard.Pause(button) just for the heck of it, again with no effect. I would have tried storyboard.Pause(storyboard) and storyboard.Pause(animation) just to exhaust the possibilities, but neither one compiles -- it wants a FrameworkElement (or FrameworkContentElement).

How do I get the storyboad to pause?

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I don't know why you are using that weired SetNameScope etc. Clearing your code i could make it work:

        //NameScope.SetNameScope(this, new NameScope());
        var storyboard = new Storyboard();

        var button = new Button { Content = "Pause", Name = "pause" };
        this.Content = button;
        //RegisterName(button.Name, button);
        var animation = new DoubleAnimation(0, 200, TimeSpan.FromSeconds(5));
        Storyboard.SetTarget(animation, button);
        Storyboard.SetTargetProperty(animation,
            new PropertyPath(FrameworkElement.WidthProperty));
        storyboard.Children.Add(animation);

        button.Click += (sender, e) => { storyboard.Pause(); };
        storyboard.Begin();