function _clickHandler(e) {
      if (_settings('mouseEnabled'))
        _self.dispatchEvent('click', {
          x: sigma.utils.getX(e) - sigma.utils.getWidth(e) / 2,
          y: sigma.utils.getY(e) - sigma.utils.getHeight(e) / 2,
          clientX: e.clientX,
          clientY: e.clientY,
          ctrlKey: e.ctrlKey,
          metaKey: e.metaKey,
          altKey: e.altKey,
          shiftKey: e.shiftKey,
          isDragging:
            (((new Date()).getTime() - _downStartTime) > 100) &&
            _hasDragged
        });

      if (e.preventDefault)
        e.preventDefault();
      else
        e.returnValue = false;

      e.stopPropagation();
      return false;
    }
The handler listening to the 'click' mouse event. It will redispatch the
click event, but with normalized X and Y coordinates.

@param {event} e A mouse event.