function show(name,s) 
  { 
    var plus = name + "_open";
    var minus = name;
    minus = getObj(minus);
    plus = getObj(plus);
    minus.style.display = (s) ? 'block' : 'none'; 
    plus.style.display = (s) ? 'none' : 'block'; 
  }

/templates/YOURTEMPL/tpl_main.ph

<!-- begin block template -->
      <tr>
        <td valign="top">
   <table border="0" width="100%" cellpadding="0" cellspacing="0">
     <tr>
       <td>
         <table border="0" cellpadding="0" cellspacing="0" width="100%">
    <tr>
      <td class="tdmenblock" width="1%"><img src="$mklib->images/m_sx.gif" border="0" class="tdmenblock" alt="" />
      </td>
      <td class="sottotitolo" width="99%" style="background-image: url('$mklib->images/m_sf.gif')" valign="middle" nowrap="nowrap">{$title}
      </td>
      <td class="tdmenblock" width="1%"><img src="$mklib->images/m_dx.gif" border="0" class="tdmenblock" alt="" />
      </td>
    </tr>
         </table>
       </td>
     </tr>
     <tr>
       <td class="tablemenu" width="100%">
         <table border="0" width="100%" cellpadding="1" cellspacing="1">
         {$content}
         </table>
       </td>
     </tr>
     <tr>
       <td>
         <table border="0" cellpadding="0" cellspacing="0" width="100%">
    <tr>
      <td class="tdmenblock" width="1%" align="right" valign="top"><img src="$mklib->images/m_sx2.gif" class="tdmenblock" alt="" />
      </td>
      <td class="tdmenblock" width="99%" style="background-image: url('$mklib->images/m_sf2.gif')"><img src="$mklib->images/m_sf2.gif" border="0" class="tdmenblock" alt="" />
      </td>
      <td class="tdmenblock" width="1%"><img src="$mklib->images/m_dx2.gif" class="tdmenblock" alt="" />
      </td>
    </tr>
         </table>
       </td>
     </tr>
   </table>
        </td>
      </tr>
      <tr>
        <td class="tdspacer">&nbsp;
        </td>
      </tr>
<!-- end block template -->

<!-- begin block template --> 
<tr> 
<td class="tablemenu" valign="top"> 
<div id='{$title}_open' style="display:none"> 
<table border="0" width="100%" cellpadding="0" cellspacing="0"> 
<tr> 
<td> 
<table class="sottotitolo" border="0" cellpadding="4" cellspacing="0" width="100%"> 
<tr> 
<td width="100%" class="sottotitolo" valign="middle" nowrap="nowrap">{$title}</td> 
<td width="*" class="sottotitolo" valign="middle" nowrap="nowrap"><a href="javascript:show('{$title}', true);"><img src="$mklib->images/plus.gif" border="0" alt="Expand Block"></a></td> 
</tr> 
</table> 
</td> 
</tr> 
</table> 
</div> 
<div id='{$title}' style="display:block"> 
<table border="0" width="100%" cellpadding="0" cellspacing="0"> 
<tr> 
<td> 
<table border="0" cellpadding="4" cellspacing="0" width="100%"> 
<tr> 
<td width="100%" class="sottotitolo" valign="middle" nowrap="nowrap">{$title}</td> 
<td width="*" class="sottotitolo" valign="middle" nowrap="nowrap"><a href="javascript:show('{$title}', false);"><img src="$mklib->images/minus.gif" border="0" alt="Collapse Block"></a></td> </tr> 
</table> 
</td> 
</tr> 
<tr> 
<td width="100%"> 
<table border="0" width="100%" cellpadding="0" cellspacing="1"> 
{$content} 
</table> 
</td> 
</tr> 
</table> 
</div> 
</td> 
</tr> 
<tr> 
<td class="tdspacer">&nbsp;</td> 
</tr> 
<!-- end block template -->