it's a combo bombo, basically..
showflat is loading the medium pic of the main image, then thumbs for the other ones (if they exist) for that post.
since lightbox uses the full sized images and does it's own thumbing, you will need to just load the full one(s) in showflat..
also, showflat would need to add some calls to the header that add the needed .js stuff (put in ubb_js)
for example:
if ($forum_info['FORUM_IS_GALLERY']) {
$js_array = array(
0 => "quickquote.js",
1 => "image.js",
2 => "gallery.js",
);
just add your .js dudes to that array .. matter of fact, you are prolly replacing image.js and gallery.js (not sure), with lightbox and prototype, scriptac..
[note] i have a minified (compressed) version of scriptac, prototype called protoculous.js that saves loading them individually.. [/note]
(oops, forgot that note is just my special tag on another forum
then in post_gallery.tpl, you'll need to make changes to add the rel="lightbox" to the image (if one) or add rel="lightbox[whatever]", so they are grouped as a strip..
also kill the thumbs area of the template, since the .js does that part for you!
then the scriptaculous and lightbox.js take over from there..
you also, might just copy/paste the lightbox.css into your extra css for each style, so you can style on a per theme basis..
the only draw back, would be in loading the full images all the time, but i don't see that as a big problem :2c:
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i think i'll have a run @ it for 7.3.1, if you haven't figured it out by then..