After sending eCard, user is taken out of Joomla-embedded gallery into standalone G2 (using JFusion)

Hello all,
I have switched from the older g2bridge to JFusion to integrate my Gallery 2 into Joomla. I have a problem that I would like to fix. After a user has sent an eCard (using Gallery 2's eCard module), upon clicking the Done button they are taken out of the Joomla/JFusion embedded G2, into standalone G2. This does not happen using the old g2bridge - but I can't keep using this as it has been "red flagged" by Joomla as being a security risk, and it is no longer supported by its developer.

I have reported this as a JFusion bug, and one of the developers has looked at it but cannot reproduce it. The original developer who ported g2bridge to JFusion's Gallery2 plugin is no longer active and the other developers are not all that familiar with Gallery 2 yet, so I thought I'd also try asking the Gallery community for help.

Steps to reproduce this:
1. Set up JFusion in Joomla, with Visual Integration mode set to Frameless
2. Go to the Joomla site and navigate to its embedded Gallery
3. Click on an album, then on a photo
4. Click Send as eCard
5. Enter details then click Send
6. The eCard has been sent now, and the user is now at the "Confirmation" screen. Click the Done button. After clicking the Done button, the user is taken to the standalone Gallery2.

Note that at eCard's "Confirmation" screen which is displayed after sending the eCard, the URL of that page is http://mysite/cms/gallery2/?g2_view=ecard.Confirmation&g2_itemId=672&g2_GALLERYSID=dbcc207bd71fd71e996fadf2c8d4824f
I am pretty sure it is the g2_GALLERYSID that does it. (I had another problem earlier which was kindly fixed by JFusion in which a temporary session ID would end up in the URL and have the same effect. This was under a different set of circumstances though.) /cms is the directory I have Joomla installed in

After clicking the "Done" button, it jumps to http://mysite/gallery2/main.php?g2_itemId=672
/gallery2 is the directory I have Gallery2 installed in.

Apart from trying this on my production site, I also set up a test site from scratch on a different machine (so it has nothing in common with the production site). The problem appeared on both in the same manner.

These are the details of my production site:

Gallery version (not just "2"): 2.3.1 core 1.3.0.1
PHP version (e.g. 5.1.6): 5.2.9 cgi-fcgi
PHPInfo Link (see FAQ):
Webserver (e.g. Apache 1.3.33): Apache 2.2.15
Database (e.g. MySql 5.0.32): mysqli 5.0.91-community, lock.system=database
Activated toolkits (e.g. NetPbm, GD): ImageMagick, Exif, Ffmpeg
Operating system (e.g. Linux): Linux sh1node2.mel.hosting-services.net.au 2.6.18-194.3.1.el5xen #1 SMP Thu May 13 13:49:53 EDT 2010 x86_64
Browser (e.g. Firefox 2.0): Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.2.7) Gecko/20100713 Firefox/3.6.7 ( .NET CLR 3.5.30729)

(and I am using Joomla 1.5.20, and JFusion 1.5.1) I have also tried the latest Gallery 2 from SVN and nightly build.

Also see my JFusion bug report: http://code.jfusion.org/issues/603 I had reported another similar issue in this report - the bug report is marked as resolved, although only the second of the two cases has been resolved. There's a .pdf file attached to this bug report with full steps I used to set up the test site.

I am not really a programmer, and am way out of my depth in trying to fix this so would appreciate any help!

If anyone is keen to have a quick look at the code for JFusion's Gallery2 plugin, it's here: http://code.google.com/p/jfusion/source/browse/#svn/branches/1.5.x/administrator/components/com_jfusion/plugins/gallery2

Thanks for your help
Andrew