I'd love to use the scene designer to lay out some edit fields, to provide users with ways to input text for name entry, editing tools, chat windows, and so on. Making such layouts in pure code goes from an annoying chore to basically a nightmare depending on layout complexity.
The EditBox objects have font size and edit field size in pixels through commands already. So I don't think it would be much of a stretch to offer adding them to scenes like the string objects. The scene editor could have a few extra properties to control the more obscure features, such as character limits and multi-line properties. We would also need a way to get them by ID tag of course, to allow us to react to input properly.