I finally found a way to add more lines to the Sites > Infos table :
It’s a little bit ugly, but it works. I simply use the action admin_footer
to add a bunch of HTML code at the end of the page, and then use jQuery to move it to the right place.
add_action('admin_footer', 'user16975_custom_options');
function user16975_custom_options(){
global $pagenow;
if( 'site-info.php' == $pagenow ) {
?><table><tr id="user16975_custom_options">
<th scope="row">My own option</th>
<td><input type="text"/></td>
</tr></table>
<script>jQuery(function($){
$('.form-table tbody').append($('#user16975_custom_options'));
});</script><?php
}
}
The good part is that as soon as the hook will be available, I can use it without big changes in my code.