Allow users to drag and drop the variable card

[FlickerSoul]

In the current version, users have to stick with the existing positioning of variable cards, and if the two var cards are further away, they have to scroll up and down to see it.

The solution can be enabling drag and drop function on the cards so users can adjust the positioning themselves. Also, they can pop the variable window out. I think that can be considered since the header is essentially a waste of space. The variable display window can use that space just fine.