Where would the human race be without thumbs?
Several times in this book I’ve wanted to use the Thumb control. The most recent occasion was the SplineKeyFrameExperiment project in the previous chapter. Two chapters earlier, I even created a PointDragger control in the CubicBezier program to compensate for the lack of the Thumb control.
Thumb is not only a component of the Slider template: It can also be used as a general-purpose manipulable control for dragging with your finger around the screen. The problem is this: With its default template, the Thumb is ugly enough to be considered “unusable.” It really needs a custom template.
Thumb derives from Control, defines an IsDragging method, and three events: DragStarted, DragDelta ...