function openWindow(link) // inspired by porneL - http://pornel.net/pups/
{
  try
  {
    var new_window = window.open(link, '_blank');
    if(new_window) return false;
  }
  catch(e){}
  return true;
}

var submit_disabled = false;

function checkRequiredFields(form_id)
{
  if(submit_disabled) return false;
  ok = true;
  fields = document.getElementsByTagName('input');
  for(var i in fields) if(fields[i].className=='text required')
  {
    if(fields[i].parentNode.parentNode.id==form_id && !fields[i].value) ok = false;
  }
  fields = document.getElementsByTagName('textarea');
  for(var i in fields) if(fields[i].className=='required')
  {
    if(fields[i].parentNode.parentNode.id==form_id && !fields[i].value) ok = false;
  }
  if(ok)
  {
    submit_disabled = true;
    setTimeout('enableSubmit()', 2000);
    return true;
  }
  alert('Musisz wypełnić wszystkie wymagane pola (oznaczone gwiazdką).');
  return false;
}

function enableSubmit(form_id)
{
  submit_disabled = false;
}

function showPreview(id, address)
{
  hideAllPreviews();
  img = new Image();
  img.onload = function()
  {
    document.getElementById(id).src = img.src;
    document.getElementById(id).style.marginTop = -parseInt(img.height + 19) + 'px';
    document.getElementById(id).style.marginLeft = -parseInt((img.width - (document.getElementById(id).parentNode.offsetWidth))/2 + 4) + 'px';
    document.getElementById(id).style.display = 'block';
  }
  img.src = address;
}

function hidePreview(id)
{
  document.getElementById(id).style.display = 'none';
}

function hideAllPreviews()
{
  ip = document.getElementsByTagName('img');
  for(var i in ip) if(ip[i].className=='preview')
  {
    ip[i].style.display = 'none';
  }
}