- Redrawable: These are elements that are redrawable within a timeline
context. They should naturally implement the interface Redrawable.

- Scrollrange: Better handling of mouseevents.

- PosLength: A Timeline element, which represents an event with a
position and length.

- HalfRange: A Timeline range indicator that covers (for now) the left
side of the Timeline.

- RhythmUI: A pane, for drawing rhythm events onto a Timeline.
- Forgot to push.