// JavaScript Document
function form_control(form){
  var warning = "Before sending you need to fill in: ";
  if(form.username.value==""){warning+="username, ";}
  if(form.useremail.value==""){warning+="email, ";}
  
  if(warning != "Before sending you need to fill in: "){
    warning = warning.substr(0,warning.length-2);
    alert(warning+".");
    return false;
  }else if(form.useremail.value.indexOf('@')==-1){
    alert('This is not a valid email address.');
    return false;
  }else if(form.useremail.value.indexOf('.')==-1){
    alert('This is not a valid email address.');
    return false;
  }else{
    adres_part=form.useremail.value.substr(form.usermail.value.indexOf('@'));
    if(adres_part.indexOf('.')==-1){
      alert('This is not a valid email address.');
      return false;
    }else{
      return true;
    }
  }
}