Elgg 1.9 issue with PicLensLite slideshow from Tidypics not working anymore

I'm trying to get Tidypics working on Elgg 1.9 but I'm stuck with not getting the slideshow to work. The slideshow is invoked by clicking on a button in the title section of a page, for example

$url = elgg_get_site_url() . "photos/siteimagesall?limit=64&offset=$offset&view=rss";
$url = elgg_format_url($url);
$slideshow_link = "javascript:PicLensLite.start({maxScale:0, feedUrl:'$url'})";
elgg_register_menu_item('title', array('name' => 'slideshow',
                                       'href' => $slideshow_link,
                                       'text' => "<img src=\"".elgg_get_site_url() ."mod/tidypics/graphics/slideshow.png\" alt=\"".elgg_echo('album:slideshow')."\">",
                                       'title' => elgg_echo('album:slideshow'),
                                       'link_class' => 'elgg-button elgg-button-action'));

On Elgg 1.8 this works without issues, i.e. I get a slideshow window open up with the next 64 images depending on the current offset served by the rss feed.

Unfortunately, it fails to work on the current dev version of Elgg 1.9. I'm testing on the same server with the same browser (though it also fails when using any other browser). The window opens (necessary libraries are loaded) but instead of the slideshow starting I get either only an empty window of PicLensLite tells me I would need to "upgrade" my flash plugin to 9.0.38 (while also telling me I do have a 11.2... version installed!).

As the browser is the same I think the problem can't be caused by a problem with the flash plugin. Also, I don't think that the code of the Tidypics plugin itself is causing the problem (no warnings, no errors, everything else runs fine, too). So, I think something that changed in Elgg core between 1.8 and 1.9 is causing the problem - first of all resulting in a seemingly wrong error about not reporting a suitable flash version being available.

PicLensLite has a fallback on lytebox in case flash is not available. But this fallback has never been used in Tidypics (lytebox.js and lytebox.css not included). I thought that the switch from fancybox to colorbox might cause the problem, so I installed the fancybox plugin, but this did not help.

I'm not sure if PicLensLite has any dependencies on jquery / jquery version. As I understand jquery has been updated in the Elgg 1.9 tree. Could this explain the problem? How could I find out if this might be the problem?

Are there any other likely reasons for the problem, starting with the way the slideshow is invoked by "javascript:PicLensLite.start({maxScale:0, feedUrl:'$url'})"?

I would be most interested in any help. I would also like to know if someone would be able to suggest a good replacement for PicLensLite (in the long run I would like to get rid of the flash plugin dependency). An alternative to PicLensLite could be solely require jquery / javascript / HTML5 / CSS3 and if anyway possible should be able to process an rss feed as source of the images for the slideshow.