Nathan Lunde-Berry

The utility of onComplete, onReverseComplete and onStart is for when timelines are nested. Those would start and complete outside of direct provocation. But I really appreciate the help thank you for responding to me so quickly.

It isn't zero duration it just starts at position zero, but that seems to work ok. The going crazy I was seeing was a lot more to do with what I had inside of "// Amazing revelations about l and t". So that's now fixed. Still things don't do what I want here. I might be able to figure it out if I had access to a onReverseStart property. Or, in my specific circumstance. Using a string "-=1000" with a min/max would also work, I think. So that for instance the parameter value could not drop below 0 or go above 50. Specifically what I'm doing is I have a viewable area, with a [image] inside it. The viewable area can get as big as x/y maximum and resizes with the image. The image gets twice as big. The image should scroll during all this resizing so that it's centred on a point. I can get everything in there in advance, except the initial scroll position. I need the initial scroll position in order to calculate where that point will be. Honestly I've just started working on this today so I may come up with a solution later on, but Dynamic Property Tweening as described by the OP sounds like it would be perfect.

This is how I did it for now, maybe it will help someone. tl = new TimelineLite onStart: => // Amazing revelations about l and t tl.to "#element3", 0.4, { left: l, top: t, overwrite: true }, 0 tl.to "#element1", 0.4, { width: w1, height: h1 }, 0 tl.to "#element2", 0.4, { width: w2, height: h2 }, 0 It's in coffeescript I hope you don't mind. But basically it will calculate what it's doing at the second it starts. Everything goes crazy for me if I scrub in reverse.