Callback not called after killing another timeline that called it. about java-universal-tween-engine HOT 4 CLOSED

That's not a bug, that's a feature :p
Actually you're keeping a reference to the Timeline "t" long after it's been 
destroyed and reset by the manager. Therefore, when you call "kill()" on it, 
you're killing a random timeline which is waiting in the pool. When you create 
the second timeline, the engine reuse the first object, but it is already 
killed and so is immediately sent back to the pool by the manager.

Actually you found a bug. In previous versions of the engine, I reset the 
tweens/timelines on pooling but also on unpooling. I removed the latter in last 
revision without considering your specific example.

Thanks for letting me know, I'll change this behavior so that manipulating 
objects that are in the pool won't have any effect.

Fixed in last commit. Tweens and timelines are reset each time they are 
unpooled.

Thanks!

I was starting to think it must be that. I sent you a PM on the badlogic forums 
yesterday to that effect. There is still a question of how to safely cancel a 
timeline that may already have completed. It may already have been unpooled and 
in use. One workaround could be to set theuser data of your timeline to a 
private member variable, then check if it still equal to that before 
cancelling. Maybe it would be worth putting in a TweenManager.killKey or 
something, so you can cancel a specific (group of) timeliness and/or 
Tween.calls safely (since killTarget dooesnt work in this case)?

Thanks again for thebawsome lib!

I answered that in libgdx forums, check your messages :)