I hope I didn't misunderstand what you mean now..
You want to create a button that's when a mouse is hovering on it, a tween is played, but when that mouse cursor leaves the certain object, the tween is played backward.
One of the main confusion I got when making that is that there are no onMouseLeave and onMouseEnter on scirra -_- (have to code it on your own for every button). Mouse on object will continuously call EaseTween.Start, making the object bigger and bigger as long as the mouse is over it. Trigger once while true could helps, but it's still painful to make that.
So, I modified the plugin and make play and stop, which is basically a version of play once that will not respond to subsequent start call. I cannot modify the original play once action since some people would use that to make dash, etc. It will be terrible if they can't dash after dashing once.
I also make reverse action which will rewind a tween.
That thing aside, this is the new behavior and looping button. I hope this is the one you need.