anchor.diff:  
     // trigger impress action (next or prev) on keyup
     document.on.keyUp.add((event) {
  -    if (event.keyCode === 9 || (event.keyCode >= 32 && event.keyCode <= 34) || (event.keyCode >= 37 && event.keyCode <= 40)) {
  -      switch (event.keyCode) {
  -        case 33: // pg up
  -        case 37: // left
  -        case 38: // up
  -          pres.prev();
  -          break;
  -        case 9:  // tab
  -        case 32: // space
  -        case 34: // pg down
  -        case 39: // right
  -        case 40: // down
  -          pres.next();
  -          break;
  -      }
  -      event.preventDefault();
  +    switch (event.keyCode) {
  +      case 33: // pg up
  +        pres.prev();
  +        break;
  +      case 37: // left
  +        pres.prev();
  +        break;
  +      case 38: // up
  +        pres.prev();
  +        break;
  +      case 9:  // tab
  +        pres.next();
  +        break;
  +      case 32: // space
  +        pres.next();
  +        break;
  +      case 34: // pg down
  +        pres.next();
  +        break;
  +      case 39: // right
  +        pres.next();
  +        break;
  +      case 40: // down
  +        pres.next();
  +        break;
       }
  +    event.preventDefault();
     });
  +
  +  /* not used atm
   
     // delegated handler for clicking on the links to presentation steps
     document.on.click.add((event) {
  
positive.code:     mCurrentStep = step;
    }
  
    Element goto(target, [duration=0]) {
      return null;
    }
  
    Element prev() {
      return null;
    }
  
    Element next() {
      return null;
    }
  }
  
  
negative.code:     return s;
    }
  
    void goto(int step) {
      // Iterate over attributes of the step jumped to and apply CSS
      mSteps[step].attributes.forEach((k,v) {
        ;
  