browser = (document.images)

  if (browser)
  {
    normal = new createArray(2)
    over = new createArray(2)

    normal[0].src = "images/logo.gif"
	normal[1].src = "images/nav_inaktiv.gif"

	
    over[0].src = "images/logo_a.gif"
	over[1].src = "images/nav_aktiv.gif"

	
  }
  
  function createArray(n)
  {
    this.length = n
    for (var i = 0; i<=n; i++)
    {
      this[i] = new Image()
    }
    return this
  }
	                
  function roll(img,x)
  {
    if (browser)
	{
	  document [img].src = over[x].src
	}
  }

  function unroll(img,x)
  {
    if (browser)
	{
	  document [img].src = normal[x].src
	}
  }