// Determine browser.

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 (isMinIE4)

    layer.style.visibility = "hidden";

}



function showLayer(layer) {

  if (isMinIE4)

    layer.style.visibility = "visible";

}



function getLeft(layer) {

  if (isMinIE4)

    return layer.style.pixelLeft;

  return -1;

}



function getTop(layer) {

  if (isMinIE4)

    return layer.style.pixelTop;

  return -1;

}



function getRight(layer) {

  if (isMinIE4)

    return layer.style.pixelLeft + getWidth(layer);

  return -1;

}



function getBottom(layer) {

  if (isMinIE4)

    return layer.style.pixelTop + getHeight(layer);

  return -1;

}



function getWidth(layer) {

  if (isMinIE4) {

    if (layer.style.pixelWidth)

      return layer.style.pixelWidth;

    else

      return layer.clientWidth;

  }

  return -1;

}



function getHeight(layer) {

  if (isMinIE4) {

    if (layer.style.pixelHeight)

      return layer.style.pixelHeight;

    else

      return layer.clientHeight;

  }

  return -1;

}



// Layer clipping.

function clipLayer(layer, clipleft, cliptop, clipright, clipbottom) {

  if (isMinIE4)

    layer.style.clip = 'rect(' + cliptop + ' ' +  clipright + ' ' + clipbottom + ' ' + clipleft +')';

}



// Layer utilities.

function getLayer(name) {

  if (isMinIE4)

    return eval('document.all.' + name);

  return null;

}