I *knew* this would be the sticking point. 

I think we should see if folks like it. Frequently when you add a card, you have some additional thing to do to it. But if the extra tab annoys folks, then I think we should do some switching logic: If no whiteboard tag, the button is clearly a "add card" button; if whiteboard tag, the button is clearly a "view card" button.

We can iterate...