<tr>
<td colspan="2" align="center">
<input type="submit" name="preview" id="preview_bt" value="Aperçu" onclick="previewWiki('mail_text', 'mail_preview', true, 'preview'); return false;" />
<tr>
<td colspan="2" align="center">
<input type="submit" name="preview" id="preview_bt" value="Aperçu" onclick="previewWiki('mail_text', 'mail_preview', true, 'preview'); return false;" />