function validateForm() {
   
   //language settings
   var intLang;  //0 = de, 1 = en, ....
   var lang     = document.addEntry.lang.value;   

   if (lang == "de") {
      intLang = 0;
   } else if (lang == "en") {
        intLang = 1;
     }
      
   //formular fields
   var title    = document.addEntry.gb_title.value;
   var name     = document.addEntry.gb_name.value;
   var email    = document.addEntry.gb_email.value;
   var homepage = document.addEntry.gb_homepage.value;
   var comment  = document.addEntry.gb_comment.value;
   
   var regExprEmail = /^(\w+)(\.?)(\w+)(\@)(\w+)(\.)(\w{2,5})$/;  //^ and $ areimportant, otherwise it doesn't work 
   strAlert = "";
   
   //error-array
   var errors = new Array(2);
   for (i = 0; i < 2; i++) {
       errors[i] = new Array(5);
   }

   errors[0][0] = "Folgende Fehler sind aufgetreten:\n";
   errors[1][0] = "The following errors ocurred:\n";   
   errors[0][1] = "Titel fehlt\n";
   errors[1][1] = "title is missing\n";
   errors[0][2] = "Name fehlt\n";
   errors[1][2] = "name is missing\n";
   errors[0][3] = "Email ungültig\n";
   errors[1][3] = "email is invalid\n";
   errors[0][4] = "Komentar fehlt\n";
   errors[1][4] = "comment is missing\n";
   
   //check values
   if (title == "") {
      strAlert = errors[intLang][1];
   } 
   
   if (name == "") {
      strAlert = strAlert + errors[intLang][2];
   }
   
   if (!(regExprEmail.exec(email)) && (email != "")) {
      strAlert = strAlert + errors[intLang][3];
   }

   if (comment == "") {
      strAlert = strAlert + errors[intLang][4];
   }   

   
   //output
   if (strAlert != "") {
      alert(errors[intLang][0] + strAlert);
      return false;
   } else {
	    document.addEntry.guestbook.value = 'add';
       return true;
     }

}


function openWin(url,w,h) {
	var win = window.open(url,"myWindow","menubar=no,resizable=no,scrollbars=yes,width="+w+",height="+h); 
}