window.onload = function() {
	var imgs = document.getElementsByTagName("img");
	// Alternativbilder für Menü vorladen
	var imgarr = new Array();
		imgarr[0] = new Image();
		imgarr[1] = new Image();
		imgarr[2] = new Image();
		imgarr[3] = new Image();
		imgarr[4] = new Image();
		imgarr[5] = new Image();
		imgarr[0].src = "img/menu/m_start2.png";
		imgarr[1].src = "img/menu/m_unternehmen2.png";
		imgarr[2].src = "img/menu/m_photo2.png";
		imgarr[3].src = "img/menu/m_wind2.png";
		imgarr[4].src = "img/menu/m_thermo2.png";
		imgarr[5].src = "img/menu/m_kontakt2.png";
	var bilder = 6;
	for (var i=0; i<imgs.length; i++) {
		var pngsrc = imgs[i].src;
		if (imgs[i].className == "pngbutton") {
			imgs[i].normsrc = pngsrc;
			imgs[i].altsrc = pngsrc.substr(0, pngsrc.indexOf(".png")) + "_act.png";
			imgs[i].onmouseover = function() {
				if (navigator.appVersion.indexOf("MSIE") != -1) {
					this.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+this.altsrc+"', sizingMethod='scale')";
				} else {
					this.src = this.altsrc;
				}
			}
			imgs[i].onmouseout = function() {
				if (navigator.appVersion.indexOf("MSIE") != -1) {
					this.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+this.normsrc+"', sizingMethod='scale')";
				} else {
					this.src = this.normsrc;
				}
			}
			// Alternativbild für Button vorladen
			imgarr[bilder] = new Image();
			imgarr[bilder].src = imgs[i].altsrc;
			bilder ++;
		}
		if (imgs[i].className == "png" || imgs[i].className == "pngbutton") {
			if (navigator.appVersion.indexOf("MSIE") != -1) {
				imgs[i].src = "img/blank.gif";
				imgs[i].style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+pngsrc+"', sizingMethod='scale')";
			}
			imgs[i].style.visibility = "visible";
		}
	}
	document.getElementById("inhalt").style.visibility = "visible";
}