//-----------------------------------------------
// Rücksprungpfeil zum Start
// Bildinformationen
var imgURL      = "back.jpg"
var imgWidth    = 20 // Breite
var imgHeight   = 30 // Hoehe

// Intervall fuer Positionspruefung in ms
var posInterval = 25

// Extraabstaende
var extraX      = 20 // Abstand fuer vertikalen Rollbalken
var extraY      = 20 // Abstand fuer horizontalen Rollbalken

// Position
var wPosition   = 3 // 1: oben links, 2: oben rechts, 3: unten rechts, 4: unten links

// Zentrieren des Hintergrundbilds
function positionierung()
{
  var ntop
  var nleft

  if(document.Marke)
  {
    with(document.Marke)
    {
      ntop  = window.pageYOffset
      nleft = window.pageXOffset
      if(wPosition == 3 || wPosition == 4)
        ntop  += innerHeight - imgHeight
      if(wPosition == 2 || wPosition == 3)
        nleft += innerWidth - imgWidth
      if(scrollbars.visible)
      {
        if(wPosition == 3 || wPosition == 4)
          ntop  -= extraX
        if(wPosition == 2 || wPosition == 3)
          nleft -= extraY
      }
      if(ntop != top || nleft != left)
      {
        top  = ntop
        left = nleft
      }
    }
  }
  else if(Marke)
  {
    with(Marke)
    {
      ntop  = document.body.scrollTop
      nleft = document.body.scrollLeft
      if(wPosition == 3 || wPosition == 4)
        ntop  += Number(document.body.clientHeight) - imgHeight
      if(wPosition == 2 || wPosition == 3)
        nleft += Number(document.body.clientWidth) - imgWidth
      if(ntop != style.top || nleft != style.left)
      {
        style.top  = ntop
        style.left = nleft
      }
    }
  }
  else
    return
}

// Initialisierung der Darstellung
function init()
{
  if(document.Marke)
    with(document.Marke.document)
    {
      open("text/html")
      write("<A HREF=\"#top\" onClick=\"positionierung(); return true\"><IMG SRC=\"" + imgURL + "\" " +
            "BORDER=0 " +
            "WIDTH=" + imgWidth + " " +
            "HEIGHT=" + imgHeight + " ALT=\"Seitenanfang\"></A>")
      close()
      width  = imgWidth
      height = imgHeight
    }
  else if(Marke)
    with(Marke)
    {
      innerHTML = "<A HREF=\"#top\" onClick=\"positionierung(); return true\"><IMG SRC=\"" + imgURL + "\" " +
                  "BORDER=0 " +
                  "WIDTH=" + imgWidth + " " +
                  "HEIGHT=" + imgHeight + " ALT=\"Seitenanfang\"></A>"
      style.width  = imgWidth
      style.height = imgHeight
    }
  else
    return

  positionierung()

  if(document.Marke)
    document.Marke.visibility = "show"
  else
    Marke.visibility = "visible"

  setInterval("positionierung()", posInterval)
}