As mention in current theme settings:
However, when we placed a slogan in default theme, the logo is never replaced but stay on top of the slogan.
The relevant code in index.template.php:
<span id="logobox">
<img id="logo" src="', $context['header_logo_url_html_safe'], '" alt="', $context['forum_name_html_safe'], '" title="', $context['forum_name_html_safe'], '" />', empty($settings['site_slogan']) ? '' : '
<span id="siteslogan">' . $settings['site_slogan'] . '</span>', '
</span>
It seems it is the same for both 1.1 and 1.0. I know the fix is simple but is this intended?