# TrillButton (filter, event)

A button, generates an event on the down-click and continues to generate events while the mouse is held down over the button.

Behavior
  Highlights on down-click, and generates an event. If held long enough, generates events repeatedly until released, canceled (by chording), or moved outside the domain of the button. When moved outside the button and still held, events are suspended until the mouse is returned to the domain of the button. At that point, the button is re-highlighted and event generation is resumed. The button is unhighlighted when the button is released or canceled.
Notes
  The initial hold-period and the repeat-period should ultimately be governed by an application-independent user profile.
Shape
  The natural shape of its child (i.e., with no shrink or stretch), plus the border around the button.