Shawn

In order to do that, I believe a custom controller would have to be introduced. It could then define a `play` method, and internally apply the delay when user calls...

> The `Animate.delay` is not part of the animation, it is a delay before the animation begins playing (ie. `AnimationController.forward()` is called), and your ability to control the animation is...

Hm, it's quite a bit of boilerplate (40 chars?), and also wouldn't play nicely with different effects: ``` TitleText().animate() .fade(end: _hideTitle? 0 : 1) .scale(end: _isTitleFocused? 1.2 : 1) ```...

Ya I think that is the core design challenge here. How to do it in a way that doesn't put any huge amt of complexity into the effects themselves. I...

To add another canonical use case to this issue. We have a view that hides some content if a dialog is open above it. The simplest way to do this...

Rather than use an adapter, its likely more straightforward for event driven animations, to cache the controller itself: ``` Text('animate me').animate( onPlay: (c) { _fadeController = c; _c.stop(); } ).fadeIn();...

Wouldn't the adapter in this case need to be hoisted out into local state as well? Otherwise it could lose state if the parent is ever rebuilt...? eg: ``` var...

Both of these options seem like more work and complication than just doing `onPlay: (c) => controller = c..stop()` and then `onPressed: () => controller.forward()`. I guess the latter saves...

fwiw this is what I would expect, going from black w/ transparency of 0, to red, would not be the same as Red(0) -> Red. I would naturally write it...

@gskinner I think the issue here is that `slivers` must be a list of `RenderSliver` children. The compiler misses it, because it accepts `List` but at some pt a runtime...