etTickMarkLength(4)
               .snapToTickMarks(true)
               .setColorForeground(color(255))
               .setColorBackground(color(0, 160, 100))
               .setColorActive(color(255,255,0))
               .setDragDirection(Knob.HORIZONTAL)
               ;
}

void draw() {
  background(myColorBackground);
  fill(knobValue);
  rect(0,height/2,width,height/2);
  fill(0,100);
  rect(80,40,140,320);
}


void knob(int theValue) {
  myColorBackground = color(theValue);
  println("a knob event. 