Errors I found

[xxxhhhyxy]

in the Dragable.cs,

1. how do you define the 3 public "UnityEventDraggable": afterGrabbed, beforeRelease and onDrop? Because I notice no difference between the latter two. I used to think that beforeRelease is for the update of the event.
   and now could you please add an UnityEventDraggable for updating?
2. for the input parameter of the 3 events above, the Pos offset is always zero, I don't know why.

[lawwong]

1.1 beforeRelease and onDrop behave differently when there are multiple grabbers. Consider following sequence:
* Grabber1 grabs
* afterGrabberGrabbed invoked (this.currentGrabber returns Grabber1 instance)
* Grabber2 grabs
* afterGrabberGrabbed invoked (this.currentGrabber returns Grabber2 instance)
* Grabber2 release
* beforeGrabberReleased invoked just before Grabber2 acutally release (hence this.currentGrabber returns Grabber2 instance)
* Grabber1 release
* beforeGrabberReleased invoked just before Grabber1 acutally release (hence this.currentGrabber returns Grabber1 instance)
* onGrabberDrop invoked since no grabber is holding (this.currentGrabber returns null)

1.2 About "add UnityEventDraggable event for updating", will add to todo list

2. The posOffset field is inherit from the base class BasePoseTracker. It means tracking offset to the final grabbed position. Use currentGrabber.grabberOrigin & currentGrabber.grabOffset to get grabber's information.