var MaxLengthLock = false; 
function MaxLengthCount(fieldObj,fieldMaxLength) 
{ 
  if (!MaxLengthLock) 
  { 
    MaxLengthLock = true; 
    if (fieldObj.value.length > fieldMaxLength) 
    { 
      alert("Text je delší než " + fieldMaxLength + " znaků!"); 
      fieldObj.value = fieldObj.value.substring(0,fieldMaxLength); 
    } 
    var percentage = parseInt(100 - (( fieldMaxLength - fieldObj.value.length) * 100)/fieldMaxLength); 
    document.getElementById(fieldObj.id + "_PBar").style.width = parseInt((parseInt(fieldObj.offsetWidth)*percentage)/100)+"px"; 
    MaxLengthLock = false; 
  } 
  }

  window.onload = function() {
  document.getElementById("submit").disabled = true;
  document.getElementById("understand1").onclick = checkIt;
}

function checkIt(){
  if (document.all||document.getElementById){
  if (document.getElementById("understand1").checked) {
  document.getElementById("submit").disabled = false;
  } else {
  document.getElementById("submit").disabled = true;
}}}

function openWindow(htmlPage,width,height) {
  window.open(htmlPage,null,
  "width="+width+",height="+height+",status=no,toolbar=no,menubar=no,location=no,resizable=yes,scrollbars=yes");
}