var nav4 = window.Event ? true : false;

function $(id) {
return document.getElementById(id);
}

function pageWidth() {
return window.innerWidth != null? window.innerWidth: document.documentElement && document.documentElement.clientWidth ? document.documentElement.clientWidth:document.body != null? document.body.clientWidth:null;
}

function pageHeight() {
return window.innerHeight != null? window.innerHeight: document.documentElement && document.documentElement.clientHeight ? document.documentElement.clientHeight:document.body != null? document.body.clientHeight:null;
}

  function absLeft(el) {
     return (el.offsetParent)? 
     el.offsetLeft+absLeft(el.offsetParent) : el.offsetLeft;
  }

  function absTop(el) {
     return (el.offsetParent)? 
     el.offsetTop+absTop(el.offsetParent) : el.offsetTop;
	}

function addEvent(obj, eventType, fn, useCaption)
// Event Handling Funktion
// -> Fügt Objekten Listener hinzu
// -> Unterscheidet zwischen Browsern
{
  if (obj.addEventListener) {
    obj.addEventListener(eventType, fn, useCaption);
    return true;
  } else if (obj.attachEvent) {
    var retVal = obj.attachEvent("on"+eventType, fn);
    return retVal;
  } else {
    return false;
  }
}



function opacity(id, opacStart, opacEnd, millisec) {
    //speed for each frame
	var speed = Math.round(millisec / 100);
    var timer = 0;

    //determine the direction for the blending, if start and end are the same nothing happens
    if(opacStart > opacEnd) {
        for(i = opacStart; i >= opacEnd; i--) {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
    } else if(opacStart < opacEnd) {
        for(i = opacStart; i <= opacEnd; i++)
            {
            setTimeout("changeOpac(" + i + ",'" + id + "')",(timer * speed));
            timer++;
        }
    }
}

//change the opacity for different browsers
function changeOpac(opacity, id) {
if(opacity == 0) {
	hideEl(id);
} 
if(opacity > 0) showEl(id);
	var object = document.getElementById(id).style;
    object.opacity = (opacity / 100);
    object.MozOpacity = (opacity / 100);
    object.KhtmlOpacity = (opacity / 100);
    object.filter = "alpha(opacity=" + opacity + ")";
} 

	function hideEl(el) {
	document.getElementById(el).style.visibility="hidden";
	}
	
	function showEl(el) {
	document.getElementById(el).style.visibility="visible";
	}