Ideally I think it would just unsnap - that is retract back like a cord on a vacuum cleaner - if it isn't attached to anything. 

On 1 Feb 2014, at 10:54 am, wrote:

When you pick up the = attached to the top left of a value outliner, and drop in in the middle of nowhere, the effect is unclear. After, if you move the target, the = re-attaches. I would think that unattaching would have broken the link (nil it out). Is there a use case for leaving it hanging out? If not, it might be good to have a drop-rejected animation that brings it back to its original target unless it is dropped on a valid new target.