n01un0, I have a good news and a bad news.
Good news is that you CAN use exgal on XOOPS 2.2.
Bad news is that you have to change it a little.
If I remmember what I did for working on 2.2, you have to get rid of
<{xoAppUrl modules/extgallery/}>">
in the template files and replace it with
<{$xoopsurl}>modules/extgallery/"
And more, in the exttgal folder, search for
$xoTheme->addStylesheet('modules/extgallery/include/style.css');
and replace with something like
$xoops_module_header = '';
$xoops_module_header .= '
.XOOPS_URL.'/modules/extgallery/include/style.css'" type="text/css" media="screen" />';
and olso replace in public-album.php for example:
$xoTheme->addMeta('meta','description',$catObj->getVar('cat_desc'));
with
$xoopsTpl->assign('xoops_meta_description', $catObj->getVar('cat_name'));
Something like that, the ideea is that you have to replace a fiew variables ( $xoTheme, xoAppUrl, ...) with the old fashion kind (xoopsurl, xoops_module_header, ...).
Please try this, is a great module, worth the effort. Maybe Zoullou could easy make a 2.2 compatible version this way.
Don't follow me. I'm lost too.