function switchtab(which) {
if (which==1) {
document.getElementById('tab1').style.display="";
document.getElementById('tab2').style.display="none";
document.getElementById('tab3').style.display="none";
document.getElementById('tab4').style.display="none";
document.getElementById('button1').setAttribute("class","ajax_box_bt_aktiv");
document.getElementById('button2').setAttribute("class","ajax_box_bt");
document.getElementById('button3').setAttribute("class","ajax_box_bt");
document.getElementById('button4').setAttribute("class","ajax_box_bt");

} else if (which==2) {
document.getElementById('tab1').style.display="none";
document.getElementById('tab2').style.display="";
document.getElementById('tab3').style.display="none";
document.getElementById('tab4').style.display="none";
document.getElementById('button1').setAttribute("class","ajax_box_bt");
document.getElementById('button2').setAttribute("class","ajax_box_bt_aktiv");
document.getElementById('button3').setAttribute("class","ajax_box_bt");
document.getElementById('button4').setAttribute("class","ajax_box_bt");
}
 else if (which==3) {
document.getElementById('tab1').style.display="none";
document.getElementById('tab2').style.display="none";
document.getElementById('tab3').style.display="";
document.getElementById('tab4').style.display="none";
document.getElementById('button1').setAttribute("class","ajax_box_bt");
document.getElementById('button2').setAttribute("class","ajax_box_bt");
document.getElementById('button3').setAttribute("class","ajax_box_bt_aktiv");
document.getElementById('button4').setAttribute("class","ajax_box_bt");
}
 else {
document.getElementById('tab1').style.display="none";
document.getElementById('tab2').style.display="none";
document.getElementById('tab3').style.display="none";
document.getElementById('tab4').style.display="";
document.getElementById('button1').setAttribute("class","ajax_box_bt");
document.getElementById('button2').setAttribute("class","ajax_box_bt");
document.getElementById('button3').setAttribute("class","ajax_box_bt");
document.getElementById('button4').setAttribute("class","ajax_box_bt_aktiv");
}

}