"Add to Lists" Scroll Bar

Description of your request or bug report:

When you have a significant amount of lists, the “add to lists” pop-up just keeps growing, and you have to scroll down the page to click the “add” button. I imagine that most people will be adding to a recent list, so it would be useful if the add button were more conveniently located by making the list titles take up less room and adding a scroll bar inside the pop-up instead.

Trello link: