chImg = function(image) {
   image.src = (image.src.indexOf('_on')>0) ? image.src.replace(/_on/,"_off") : image.src.replace(/_off/,"_on");
  }

  post = function(target,event,id) {
    var form = document.forms[id];
    form.action = target;
    if (form.event) form.event.value = event;
    form.submit();
  }

  ask = function(question) {
    return confirm(question);
  }

  panels = 2;
  chgPanel = function(panel) {
    for (i=1;i<=panels;i++) {
      $('panel'+i).style.display=(i==panel)?'block':'none';
    }
  }