// funkcja przełącza TabSheet
function changeTabSheet() {
  if ((!this) || (this.className == 'front')) return false;
  var ul = this.parentNode;
  var li = ul.getElementsByTagName('LI');
  for (var i=0; i<li.length; i++ ) {
    li[i].className = (li[i]==this) ? li[i].className.replace('back','front') : li[i].className.replace('front','back');
    var pg = document.getElementById('page'+i);
    if (pg) {
      pg.className = (li[i]==this)? pg.className.replace('back','front') : pg.className.replace('front','back');
    }
  }
  return false;
}
function activateTabSheet() {
  var ul = document.getElementsByTagName('UL');
  for( i=0; i<ul.length; i++ ) {
    if (ul[i].className != 'tabs') continue;
    var li = ul[i].getElementsByTagName('LI');
    for( j=0; j<li.length; j++ )
      li[j].onclick = changeTabSheet;
  }
}


window.onload = function() {
  activateTabSheet();
}