Ciao.
Lo snippet:
Codice PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<
html xmlns="http://www.w3.org/1999/xhtml" xml:lang="it" lang="it" dir="ltr">
<
head>
<
title>Test</title>
<
meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<
script type="text/JavaScript">
/* shortcut dom */
function _createElement(el,obj){
    var 
_eldocument.createElement(el);
    for(var 
prop in obj){
         
_el.setAttribute(prop,obj[prop]);
    }
    return 
_el;
};
function 
_createTextNode(text){
    return 
document.createTextNode(text);
};
function 
_removeChild(parent,child){
    if(
child != null){
        
parent.removeChild(child);
    }
};
function 
console(obj){
    
this.add = function(message) {
        
obj.innerHTML message;
    };
};
/* Events */
function addEvent(elmevTypefnuseCapture){
    if (
elm.addEventListener){
            
elm.addEventListener(evTypefnuseCapture);
            return 
true;
    } else if (
elm.attachEvent) {
        var 
elm.attachEvent('on' evTypefn);
        return 
r;
    } else {
        
elm['on' evType] = fn;
    }
};
function 
getTarget(e){
        var 
target window.event window.event.srcElement e.target null;
        if (!
target){return false;}
        return 
target;
};
function 
cancelClick(e){
    if (
window.event){
        
window.event.cancelBubble true;
        
window.event.returnValue false;
        return;
    }
    if (
e){
        
e.stopPropagation();
        
e.preventDefault();
    }
};

/* Utility */
function $(){
    var 
elements = new Array();
    for (var 
0;i<arguments.length;i++){
        var 
element arguments[i];
        if (
typeof element == 'string'){
          
element document.getElementById(element);
        }
        if (
arguments.length == 1){
          return 
element;
        }
        
elements.push(element);
      }
    return 
elements;
};
function 
trim(s) {
  while ((
s.substring(0,1) == ' ') || (s.substring(0,1) == '\n') || (s.substring(0,1) == '\r')) {
    
s.substring(1,s.length);
  }
  while ((
s.substring(s.length-1,s.length) == ' ') || (s.substring(s.length-1,s.length) == '\n') || (s.substring(s.length-1,s.length) == '\r')) {
    
s.substring(0,s.length-1);
  }
  return 
s;
};
function 
addNumberToString(str,num){           
    return 
str.concat(parseInt(num));
};
/* Validation */
function isEmpty(val) {
   return !/\
S/.test(val);

/* Job */
function buildError(el,msg){
    var 
showError_createElement(el,{id:'show-error'});
    
showError.appendChild(_createTextNode(msg));
    return 
showError;
}
function 
ManageTag(){
    var 
targetnull;
    var 
seedTag'tag-name-';
    var 
seedTagAction'action-tag-';
    function 
getFocus(target){
        var 
firstLitarget.getElementsByTagName('li').item(0);
        if(!
firstLi){return}
        var 
forFocusfirstLi.getElementsByTagName('form').item(0);
        if(
forFocus.elements[3].getAttribute('name')=='tag_new_name'){
            
forFocus.elements[3].focus();
        }
    }
    function 
getTagId(e){
        var 
targetgetTarget(e);
        
cancelClick(e);
        var 
elementIdtarget.getAttribute('id');
        return 
parseInt(elementId.split("-")[2]);
    }
    function 
deleteConfirm(tagName){
        return 
window.confirm("You are about to delete this tag \n'"+tagName+'\'\n\'OK\' to delete, \'Cancel\' to stop.');
    }
    function 
deleteResponse(xhr){}
    function 
deleteRequest(e){
        var 
currentTagIdgetTagId(e);
        
alert(currentTagId);
    }
    function 
updateRequest(e){
        var 
tagNewName'';
        var 
currentTagIdgetTagId(e);
        if(
isNaN(currentTagId)){return;}
        var 
currentActionElementIdaddNumberToString(seedTagAction,currentTagId);
        var 
currentActionElement= $(currentActionElementId);
        if(!
currentActionElement){return;}
        var 
_formcurrentActionElement.getElementsByTagName('form').item(0);
        if(
_form.elements[3].getAttribute('name')=='tag_new_name'){
            
tagNewNametrim(_form.elements[3].value);
        }
        var 
_fieldsetcurrentActionElement.getElementsByTagName('fieldset').item(0);
        var 
showErrorbuildError('span','The field is required !');
        
_removeChild(_fieldset,$('show-error'));
        if(
isEmpty(tagNewName)){
                
_fieldset.appendChild(showError);
                
_form.elements[3].focus();
                return;
        }
    }
    function 
init(){
        if(!
document.getElementById || !document.getElementsByTagName || !document.createTextNode){return;}
        
target= $('ul-tag-list');
        var 
regexDelete = /^delete\-tag\-[1-9]\d{0,9}$/;
        var 
regexUpdate = /^update\-tag\-[1-9]\d{0,9}$/;
        var 
inputListtarget.getElementsByTagName('input');
        for(var 
i=0;i<inputList.length;i++){
            var 
typeinputList.item(i).getAttribute('type').toLowerCase();
            if(
type=='submit'){
                
inputList.item(i).removeAttribute('type');
                
inputList.item(i).setAttribute('type','button');
                var 
currentTagIdinputList.item(i).getAttribute('id');
                if(
regexDelete.test(currentTagId)){
                    
addEvent(inputList.item(i),'click',deleteRequest,false);
                }
                else if(
regexUpdate.test(currentTagId)){
                    
addEvent(inputList.item(i),'click',updateRequest,false);
                }
            }
        }
        
getFocus(target);
    }
    
init();
}
addEvent(window,'load',ManageTag,false);
</script>
</head>
<body>
<div id="heading">
<h1>Test</h1>
</div>
<div id="container">
<div id="navigation">
<div id="content">
<ul id="ul-tag-list">
<li class="li-tag-list" id="action-tag-10">
<form action="/yasin/PHP5/myscripts/blog2/mvc18/admin/manage-tags.php?action=action_tag" method="post">
<fieldset>
<input name="tag_id" type="hidden" value="10"  />
<input name="tag_name" type="text" id="tag-name-10" class="tag-list-disabled" disabled="disabled" value="prova"  />
<input name="tag_new_name" type="text" value=""  />
<input name="tag_action" type="submit" value="Delete" class="tag-list-button" id="delete-tag-10"  />
<input name="tag_action" type="submit" value="Update" class="tag-list-button" id="update-tag-10"  />
<input name="check_insert" type="hidden" value="1188289284"  />
</fieldset>
</form>


<li class="li-tag-list" id="action-tag-7">
<form action="/yasin/PHP5/myscripts/blog2/mvc18/admin/manage-tags.php?action=action_tag" method="post">
<fieldset>
<input name="tag_id" type="hidden" value="7"  />
<input name="tag_name" type="text" id="tag-name-7" class="tag-list-disabled" disabled="disabled" value="Events"  />
<input name="tag_new_name" type="text" value=""  />
<input name="tag_action" type="submit" value="Delete" class="tag-list-button" id="delete-tag-7"  />
<input name="tag_action" type="submit" value="Update" class="tag-list-button" id="update-tag-7"  />
<input name="check_insert" type="hidden" value="1188289284"  />
</fieldset>
</form>

<li class="li-tag-list" id="action-tag-6">
<form action="/yasin/PHP5/myscripts/blog2/mvc18/admin/manage-tags.php?action=action_tag" method="post">
<fieldset>
<input name="tag_id" type="hidden" value="6"  />
<input name="tag_name" type="text" id="tag-name-6" class="tag-list-disabled" disabled="disabled" value="MySql"  />

<input name="tag_new_name" type="text" value=""  />
<input name="tag_action" type="submit" value="Delete" class="tag-list-button" id="delete-tag-6"  />
<input name="tag_action" type="submit" value="Update" class="tag-list-button" id="update-tag-6"  />
<input name="check_insert" type="hidden" value="1188289284"  />
</fieldset>
</form>

<li class="li-tag-list" id="action-tag-3">
<form action="/yasin/PHP5/myscripts/blog2/mvc18/admin/manage-tags.php?action=action_tag" method="post">
<fieldset>
<input name="tag_id" type="hidden" value="3"  />
<input name="tag_name" type="text" id="tag-name-3" class="tag-list-disabled" disabled="disabled" value="Ajax"  />
<input name="tag_new_name" type="text" value=""  />
<input name="tag_action" type="submit" value="Delete" class="tag-list-button" id="delete-tag-3"  />
<input name="tag_action" type="submit" value="Update" class="tag-list-button" id="update-tag-3"  />
<input name="check_insert" type="hidden" value="1188289284"  />
</fieldset>

</form>

<li class="li-tag-list" id="action-tag-1">
<form action="/yasin/PHP5/myscripts/blog2/mvc18/admin/manage-tags.php?action=action_tag" method="post">
<fieldset>
<input name="tag_id" type="hidden" value="1"  />
<input name="tag_name" type="text" id="tag-name-1" class="tag-list-disabled" disabled="disabled" value="php5"  />
<input name="tag_new_name" type="text" value=""  />
<input name="tag_action" type="submit" value="Delete" class="tag-list-button" id="delete-tag-1"  />
<input name="tag_action" type="submit" value="Update" class="tag-list-button" id="update-tag-1"  />
<input name="check_insert" type="hidden" value="1188289284"  />
</fieldset>
</form>
[/list]
</div>
</div>

<div id="footer">

</div>
</body>
</html> 

Se click su update mi appare The field is required !
come deve essere se ci riclicco mi rimane ............
però se ad esempio ho cliccato sul primo
update e poi vado sul secondo invece di apparire
The field is required ! mi appare in firebug node was not
found perchèèè