Name for list item selection/movement bar?

So I want to create a simple utility that lets me select or rearrange items in my lists through the inspector, much like say Mecanim's transitions or something. I can't figure out exactly what they're called though, nor by extension the function I'd have to call to make one appear.

I'm aware that Advanced Inspector does this, but I can't rely on licensed extensions for this part of my game.

Is there a particular name for one of these selectable/rearrangeable list "tabs" or the like?