function activate(theTab) {
	/* unset all tabs */
//	home_start.className = "inact_start";
//	home.className = "inact";
//	home_end.className = "inact_end";
//
//	maschinen_start.className = "inact_start";
	maschinen.className = "inact";
//	maschinen_end.className = "inact_end";
//	
//	kontakt_start.className = "inact_start";
	kontakt.className = "inact";
//	kontakt_end.className = "inact_end";	
//	
//	impressum_start.className = "inact_start";
	impressum.className = "inact";
//	impressum_end.className = "inact_end";	
//	
//	about_start.className = "inact_start";
	about.className = "inact";
//	about_end.className = "inact_end";		
	
	/* set selected tab */
//	document.getElementById(theTab + "_start").className = "act_start";
	document.getElementById(theTab).className = "act";
//	document.getElementById(theTab + "_end").className = "act_end";
	
	/* unset all content */
	document.getElementById("content_maschinen").style.display = "none";
	document.getElementById("content_kontakt").style.display = "none";
	document.getElementById("content_impressum").style.display = "none";
	document.getElementById("content_about").style.display = "none";
	
	/* set selected content */
	var theContentDiv = document.getElementById("content_" + theTab).style.display = "block";
	
}