code: function finger_moved(e) {
          var touch = e.touches[0] || e.changedTouches[0];
          var delta_x = touch.clientX - gesture_start_x;
          var delta_y = touch.clientY - gesture_start_y;
          return Math.sqrt(delta_x*delta_x + delta_y*delta_y) >= guac_touchscreen.clickMoveThreshold;
      }
docs: Returns whether the given touch event exceeds the movement threshold for
  clicking, based on where the touch gesture began.
  
  @private
  @param {TouchEvent} e The touch event to check.
  @return {Boolean} true if the movement threshold is exceeded, false
  otherwise.