<!-- Open new window  -->
function openwin(url)
{
    if(window.open(url,'','width=800,height=600,left=0,top=0,scrollbars=yes,location=yes,resizable=yes'))
    {    
        return false;
    }
    else 
    {    
        return true;
    }
}
/*************************************************
 ** AddLoad event function
 *************************************************/
function addLoadEvent(func) {
    var oldonload = window.onload;
    if (typeof window.onload != 'function') {
        window.onload = func;
    } else {
        window.onload = function() {
            if (oldonload) {
                oldonload();
            }
            func();
        }
    }
}
addLoadEvent(function() {
    setTimeout(initOverLabels, 50);
})
/****************************************************
 ** Validate Login Form
 ****************************************************/ 
function validateLogin(formular)	{
		if (formular.txtLogin.value=="")  {
        alert("Uživatelské jméno musíte vyplnit!");
        formular.txtLogin.focus();
        return false;
    } 
    else if (formular.txtHeslo.value=="") {
        alert("Heslo musíte vyplnit!");
        formular.txtHeslo.focus();
        return false;
    } 
    else 
        return true;
}
function initOverLabels () {
  if (!document.getElementById) return;  	

  var labels, id, field;

  // Set focus and blur handlers to hide and show 
  // LABELs with 'overlabel' class names.
  labels = document.getElementsByTagName('label');
  for (var i = 0; i < labels.length; i++) {
	
    if (labels[i].className == 'overlabel') {

      // Skip labels that do not have a named association
      // with another field.
      id = labels[i].htmlFor || labels[i].getAttribute('for');
      if (!id || !(field = document.getElementById(id))) {
        continue;
      } 

      // Hide any fields having an initial value.
      if (field.value !== '') {
        hideLabel(field.getAttribute('id'), true);
      }

      // Set handlers to show and hide labels.
      field.onfocus = function () {
        hideLabel(this.getAttribute('id'), true);
      };
      field.onblur = function () {
        if (this.value === '') {
          hideLabel(this.getAttribute('id'), false);
        }
      };

      // Handle clicks to LABEL elements (for Safari).
      labels[i].onclick = function () {
        var id, field;
        id = this.getAttribute('for');
        if (id && (field = document.getElementById(id))) {
          field.focus();
        }
      };

    }
  }
};

function hideLabel (field_id, hide) {
  var field_for;
  var labels = document.getElementsByTagName('label');
  for (var i = 0; i < labels.length; i++) {
    field_for = labels[i].htmlFor || labels[i].getAttribute('for');
    if (field_for == field_id) {
     labels[i].style.textIndent = (hide) ? '-1000px' : '0px';
			return true;
    }
  }
}
<!-- Validate form -->
function validate2(formular)
{
    if (formular.jmeno2.value=="")
    {
        alert("Meno musíte vyplnit!");
        formular.jmeno2.focus();
        return false;
    } 
    else if (formular.prijmeni.value=="")
    {
        alert("Priezvisko musíte vyplnit!");
        formular.prijmeni.focus();
        return false;
    }   
    else if (formular.telefon.value=="")
    {
        alert("Telefon musíte vyplnit!");
        formular.telefon.focus();
        return false;
    }
    else if (formular.question.value != "EUROBUSINESS")
    {
        alert("Overeni musíte vyplnit!");
        formular.question.focus();
        return false;
    }
    else
    { 
        return true;
	}
}