@goldsky : Thanks for the fix. That works. FWIW, I changed the "zoom" block to add in the sliding transition, rather than try to get things to work the other way around. So my (working) block of code looks like :
if ($ssParams['ss_config'] == 'zoom') {
$modx->regClientStartupScript(MODX_BASE_URL . 'assets/libs/slideshows/smoothgallery/scripts/mootools-1.2.1-core-yc.js');
$modx->regClientStartupScript(MODX_BASE_URL . 'assets/libs/slideshows/smoothgallery/scripts/mootools-1.2-more.js');
$modx->regClientStartupScript(MODX_BASE_URL . 'assets/libs/slideshows/smoothgallery/scripts/ReMooz.js');
$modx->regClientStartupScript(MODX_BASE_URL . 'assets/libs/slideshows/smoothgallery/scripts/jd.gallery.js');
$modx->regClientStartupScript(MODX_BASE_URL . 'assets/libs/slideshows/smoothgallery/scripts/jd.gallery.transitions.js');
$modx->regClientStartupHTMLBlock('
<script type="text/javascript">
function startGallery() {
var myGallery = new gallery($(\'myGallery\'), {
timed: false,
useReMooz: true,
defaultTransition: "fadeslideleft",
embedLinks: false
});
}
window.addEvent(\'domready\',startGallery);
</script>
');
}
It looks like something in the way the smoothgallery javascript is written prevents any of the the lightboxes (e.g. colorbox, highslide, etc.) from working, at least as far as I can tell. And though there have been plenty of requests on the smoothgallery site asking for advice on getting something like lightbox to work, no working solution seems to have been posted. I’ll take a look at the code and if I find a way of getting the integration to work, I’ll post about it. (I’m noting this here so that if anyone else decides to go down this road they won’t spend as much time on it as I have

)
Thanks again for your help. What I’ve got working now will do for the time being.
Matt