docs: function(evt)
  	{
  		// Special case for mousemove and mousedown we check the buttons
  		// if it exists because which is 0 even if no button is pressed
  		if ('buttons' in evt && (evt.type == 'mousedown' || evt.type == 'mousemove'))
  		{
  			return evt.buttons == 1;
  		}
  		else if ('which' in evt)
  		{
  	        return evt.which === 1;
  	    }
  		else
  		{
  	        return evt.button === 1;
  	    }
  	}