function changeButton(bhash, overout) {
        if(overout == 'over') {
            document.getElementById('anfang_'+bhash).src = 'fileadmin/tmpl/images/button/btn_or_left.gif';          
            document.getElementById('ende_'+bhash).src = 'fileadmin/tmpl/images/button/btn_or_right.gif';
            document.getElementById('mitte_'+bhash).className = 'buttonMitteOver';
        }
        else {
            document.getElementById('anfang_'+bhash).src = 'fileadmin/tmpl/images/button/btn_bl_left.gif';
            document.getElementById('ende_'+bhash).src = 'fileadmin/tmpl/images/button/btn_bl_right.gif';
            document.getElementById('mitte_'+bhash).className = 'buttonMitteNormal';
        }
      }