@Override
	protected void drawableStateChanged() {
		super.drawableStateChanged();
		if (mThumb != null && mThumb.isStateful()) {
			int[] state = getDrawableState();
			mThumb.setState(state);
		}
		invalidate();
	}
Notification that the user has finished a touch gesture. Clients may
want to use this to re-enable advancing the seekarc.

@param seekArc
           The SeekArc in which the touch gesture began
SeekArc_library/src/com/triggertrap/seekarc/SeekArc.java