Hi Marc and Hugues,

I have improved the UI a little bit for this feature. Now the UI appears less cluttered. I have added a link to screenshot [1].The user is trying to add constraints to `table_2` in the example. Please comment.

[1] - https://drive.google.com/file/d/0B4NmZAt35XrgRi1ubFk3YVp0UXhLYWFiZTJVaDVET093aDlr/edit?usp=sharing