I went over your code and corrected it. You need to
install the mod you mentioned for this to work. This should do the trick, assuming you have that mod installed you can use this in a PHP block or article :
global $scripturl, $settings, $modSettings;
echo '
<style type="text/css">
.nice_tooltip_fgclass {
background-color: ' . $modSettings['NiceTooltips_FGCOLOR'] . ';
opacity: ' . $modSettings['NiceTooltips_OPACITY'] / 100 . ';
}
.nice_tooltip_bgclass {
background-color: ' . $modSettings['NiceTooltips_BGCOLOR'] . ';
opacity: ' . $modSettings['NiceTooltips_OPACITY'] / 100 . ';
}
</style>';
echo '
<script language="JavaScript" type="text/javascript" src="' . $settings['default_theme_url'] . (!empty($modSettings['NiceTooltips_scripturl']) ? '/' . $modSettings['NiceTooltips_scripturl'] : '') . '/overlib_mini.js"></script>';
echo '
<script language="JavaScript" type="text/javascript" src="' . $settings['default_theme_url'] . (!empty($modSettings['NiceTooltips_scripturl']) ? '/' . $modSettings['NiceTooltips_scripturl'] : '') . '/overlib_adaptive_width.js"></script>';
$what=ssi_recentTopics('10', NULL, 'array');
echo '
<table border="0" width="100%" cellspacing="1" cellpadding="3" class="bordercolor">';
echo '
<tr class="catbg3"><td align="center">Subject</td><td align="center">Board</td><td align="center">Member</td><td align="center">Date & Time</td></tr>';
$bg=false;
foreach ($what as $topic)
{
$popup = NiceTooltip($topic['preview'], $topic['subject']);
echo '<tr class="windowbg' , $bg ? '2' : '' , '">';
$bg = !$bg;
echo '<td valign="middle"><a href="' , $topic['href'] , '"' , $popup , '>' , $topic['subject'] , '</a>';
// Is this topic new? (assuming they are logged in!)
if (!$topic['new'] && $context['user']['is_logged'])
echo '<a href="', $scripturl, '?topic=', $topic['topic'], '.from', $topic['time'], '#new"><img src="', $settings['images_url'], '/', $context['user']['language'], '/new.gif" alt="New', $txt[302], '" border="0" align="right", valign="absmiddle" /></a>';
echo '</td>
<td valign="middle" >', $topic['board']['link'], '</td>';
echo '</td>
<td valign="middle" >', $topic['poster']['link'], '</td>
<td valign="middle" >';
if ($settings['images_url'] != $settings['theme_url'] . '/images' || file_exists($settings['theme_dir'] . '/images/icons/last_post.gif'))
echo '<a href="', $topic['href'], '"><img src="', $settings['images_url'], '/icons/last_post.gif" alt="', $txt[111], '" title="', $txt[111], '" border="0" style="float: right;" /></a>';
echo '<span class="smalltext">', $topic['time'], '</span></td></tr>';
}
echo '</table>';
Because you are using SSI, there is a limit to what is shown in the message body. With the default SSI settings it is limited to 128 characters.
You can change this by going to SSI.php and finding (around line 372)
if ($func['strlen']($row['body']) > 128)
$row['body'] = $func['substr']($row['body'], 0, 128) . '...';
Change both 128 to whatever you want...
Hope that get's you on track.

Screenshot attached...I din't change my colours, that's why it doesn't match, but it works.