var NS4 = (document.layers) ? true : false;
var IE4 = (document.all && !document.getElementById) ? true : false;
var IE5 = (document.all && document.getElementById) ? true : false;
var NS6 = (!document.all && document.getElementById) ? true : false;

var tid;
var imgarray = new Array(4);
imgarray[0] = "../images/testata/menu_ann_txt.gif";
imgarray[1] = "../images/testata/menu_help_txt.gif";
imgarray[2] = "../images/testata/menu_lav_txt.gif";
imgarray[3] = "../images/testata/menu_reg_txt.gif";
imgarray[4] = "../images/testata/menu_pub_txt.gif";

var activeLayer = "";
window.onresize = WinResize;

function hideOnTimeout() {
    tid = setTimeout("hideAllLayers()",1500);
}

function positionLayer(layerName) {
	if (window.innerWidth) {
		scw = parseInt(window.innerWidth);
	} else {
		scw = parseInt(document.body.clientWidth);
	}

	if (document.body.scrollLeft) {
		scw -= parseInt(document.body.scrollLeft);
	} else if (window.pageXOffset) {
		scw -= parseInt(window.pageXOffset);
	} /*else {
		if (navigator.product == 'Gecko') {
			scw -= 15;
		}
	}*/
  if (scw < 785) { scw = 785; }
 	rpos = ((scw - 785) / 2);

  if (NS4) {
  	dom = document.layers[layerName]
		dom.left = rpos;
  } else if (IE4) {
		dom = document.all[layerName];
		dom.style.left = rpos;
  } else if  (IE5 || NS6){
		dom = document.getElementById(layerName)
    dom.style.left = (parseInt(rpos)) + "px";
	}


}

function showLayer(layerName) {
	positionLayer(layerName);

	if (NS4) {
    document.layers[layerName].visibility ="show";
 	} else if (IE4 ) {
    document.all[layerName].style.visibility="visible";
	} else if  (IE5 || NS6) {
    document.getElementById(layerName).style.visibility = "visible";
	}
  activeLayer = layerName;
}

function hideLayer(layerName) {
  if (NS4) {
    document.layers[layerName].visibility ="hidden";

	} else if (IE4 || IE5) {
    document.all[layerName].style.visibility="hidden";

	} else if  (NS6) {
    document.getElementById(layerName).style.visibility = "hidden";

	}
  activeLayer = "";
  num = imagenumFromMenu(layerName).valueOf();
  img = eval("document.image" + num);
	swapImage(img, imgarray[num-1]);

}

function hideAllLayers() {
  div = document.getElementsByTagName("div");

  for (var i = 0; i < div.length; i++) {
    if ( ((div[i].id).substring(0,4)) == "menu") {
      hideLayer(div[i].id);
    }
  }
}

function imagenumFromMenu(layerName) {
  return layerName.substring(4, layerName.length);
}


function WinResize() {
  if (activeLayer) {
	  positionLayer(activeLayer);
	}
}