Photoshop: ability to toggle off the deletion behavior of "Subtract from selection"

I would like to be able to toggle off the auto-delete behavior of the selection tools' "Subtract from selection" boolean option, which happens after I move a selection. 

http://imgur.com/a/EFBty

I use Photoshop for sketching people, and being able to move body parts—like the whole arm and then just the hand by deselecting everything that isn't the hand—would be extremely helpful when getting proportions right. 

(Accidentally deleting content by moving and then subtracting from the selection is getting really frustrating.)