Rename drag.subject to drag.data?

[mbostock]

The word subject implies it’s the thing doing the dragging, not the thing being dragged. We could use the word object, but I think data would be better.

Or not. Subject is defined as “a person or thing that is being discussed, described, or dealt with.” Which could be appropriate.

[altocumulus]

When first running into subject, I intuitively got it right. I'd prefer subject over data or object.

[mbostock]

Yeah, it’s probably fine.