Agregamos antes:
<br /><table class="tborder" cellpadding="5" cellspacing="1" border="0" width="100%" >
<tr><td class="thead"><strong>Enlaces Permanentes</strong></td></tr>
<tr><td class="trow2">
<table cellspacing="1" border="0" width="100%">
<tr>
<td><strong>Enlace del Tema:</strong></td>
<td><textarea name="link" cols="100" READONLY onfocus="javascript: this.select()" rows="1">{$mybb->settings['bburl']}/{$thread['threadlink']}</textarea></td>
</tr>
<tr>
<td><strong>Codigo Foros:</strong></td>
<td><textarea name="bbkodu" cols="100" READONLY onfocus="javascript: this.select()" rows="1">[url={$mybb->settings['bburl']}/{$thread['threadlink']}[/url]</textarea></td>
</tr>
<tr>
<td><strong>Codigo Webs:</strong></td>
<td><textarea name="htmlkodu" cols="100" READONLY onfocus="javascript: this.select()" rows="1"><a href="{$mybb->settings['bburl']}/{$thread['threadlink']}">{$thread['subject']}</a></textarea></td>
</tr>
</table>
</td>
</tr>
</table>
Ahora, abrimos el archivo showthread.php y buscamos esto:
// Fetch some links
$next_oldest_link = get_thread_link($tid, 0, "nextoldest");
$next_newest_link = get_thread_link($tid, 0, "nextnewest");
Agregamos esta linea exactamente despues:
$thread['threadlink'] = get_thread_link($tid, 0);
Quedando asi:
// Fetch some links
$next_oldest_link = get_thread_link($tid, 0, "nextoldest");
$next_newest_link = get_thread_link($tid, 0, "nextnewest");
$thread['threadlink'] = get_thread_link($tid, 0);