I've been here for hours looking for this, I know it should be straightforward to use the code from searchnew.php or upload.php somewhere, but I can't for the life of me figure it out. All I am after is a way to have an album dropdown list that works no matter which theme is selected, which will allow the user to choose an album via a dropdown list, rather than have to return to the top level each time and navigate back into another category.
I'm no expert with PHP so if anyone can help please shout up.
Decided to post a solution, albeit not via Code, grab a copy of SiteXpert and get it to spider your installation, it can produce drop downs, navigable customisable menus etc.
http://www.xtreeme.com/sitexpert/ (http://www.xtreeme.com/sitexpert/)
Not the perfect solution if your gallery is constantly changing categories etc, but it suits my purposes for the moment.