[Seaside] Component traits library?

[itsme213]

What would you add to a library of components traits?

- Collapsible? can be expanded and collapsed
- Draggable?
- Moveable? can be moved as on a canvas
- Resizable:
- Spawnable: can be spawned off into a window of its own
- Scrollable: grow a scrollbar when needed

- Others??

Would these be a reasonable use of traits? Seems like handy behaviors to mix 
in as needed but I'm not confident about the implications.

- Sophie