var isMinNS4 = (navigator.appName.indexOf("Netscape") >= 0 &&
                parseFloat(navigator.appVersion) >= 4) ? 1 : 0;
var isMinIE4 = (document.all) ? 1 : 0;
var isMinIE5 = (isMinIE4 && navigator.appVersion.indexOf("5.")) >= 0 ? 1 : 0;

//-----------------------------------------------------------------------------
// Layer visibility.
//-----------------------------------------------------------------------------

function hideLayer(layer) {

  if (isMinNS4)
    layer.visibility = "hide";
  if (isMinIE4)
    layer.style.visibility = "hidden";
}

function showLayer(layer) {

  if (isMinNS4)
    layer.visibility = "show";
  if (isMinIE4)
    layer.style.visibility = "visible";
}

function isVisible(layer) {

  if (isMinNS4 && layer.visibility == "show")
    return(true);
  if (isMinIE4 && layer.style.visibility == "visible")
    return(true);

  return(false);
}

//-----------------------------------------------------------------------------
// Layer positioning.
//-----------------------------------------------------------------------------

function moveLayerTo(layer, x, y) {

  if (isMinNS4)
    layer.moveTo(x, y);
  if (isMinIE4) {
    layer.style.left = x;
    layer.style.top  = y;
  }
}

function moveLayerBy(layer, dx, dy) {

  if (isMinNS4)
    layer.moveBy(dx, dy);
  if (isMinIE4) {
    layer.style.pixelLeft += dx;
    layer.style.pixelTop  += dy;
  }
}



function getzIndex(layer) {

  if (isMinNS4)
    return(layer.zIndex);
  if (isMinIE4)
    return(layer.style.zIndex);

  return(-1);
}

function setzIndex(layer, z) {

  if (isMinNS4)
    layer.zIndex = z;
  if (isMinIE4)
    layer.style.zIndex = z;
}


//-----------------------------------------------------------------------------
// Window and page properties.
//-----------------------------------------------------------------------------

function getWindowWidth() {

  if (isMinNS4)
    return(window.innerWidth-6);
  if (isMinIE4)
    return(document.body.clientWidth);
  return(-1);
}

function getPageWidth() {

  if (isMinNS4)
    return(document.width);
  if (isMinIE4)
    return(document.body.scrollWidth);
  return(-1);
}

function getOffset()
{
	var wid = getWindowWidth();

	if (isMinNS4) {
		if (wid <= 779) {  return 0 ; }
		if (wid > 779) {  return (wid -779)/2-6 ;	}
	}
	if (isMinIE4) {
		if (wid <= 779) {  return 0 ; }
		if (wid > 779) {  return (wid -779)/2 ;	}
	}
}