How Undo Last Action?

How can one undo the last action taken on Fences?

How can one restore to the last, or a Snapshot?

Where is the Snapshot stored?   


I wanted to move all icons from one fence to another and I clicked one icon and then Cntl A, and dragged and dropped it.

Cntrl A, instead of selecting all icons from that one fence, selected all icons from all fences.   

Now I would like to restore or undo this error, preferably without having to move each icon individually.