AnimationCurve.MoveKey  

function MoveKey (index : int, key : Keyframe) : int

Description

Removes the keyframe at index and inserts key.

If a keyframe already exists at key.time the time of the old keyframe's position /key[index].time/ will be used instead. This is the desired behaviour for dragging keyframes in a curve editor. Returns the index of the keyframe after moving it.