DoubleClick example does not initialize the double click threshold time

The DoubleClick example, the setup() function is missing a call to the Button::setdoubleclickThreshold(time) member. Therefore double clicks are never detected. 

void setup(){
  Serial.begin(9600);
  Serial.println("Started");
  pinMode(ledPin,OUTPUT);                //LED on pin 12
  Button1.setdoubleclickThreshold(500) ;   //---- missing this
}