Ani is a great library (thanks Benedikt!), but I have noticed that it can set the variable after the onEnd method has been called. This came to light when my onEnd method set the value of the variable (to another value due to a change of 'state') but was mysteriously changed after this. It took a lot of tracking down as I obviously thought it was my code altering the value, but it was Ani all along! To fix it I had to reset the value before the next draw (but after the onEnd call).   This is not a problem when the animation end value is not changed in the onEnd method, so perhaps it has never cropped up before?