Sorry about the late reply, but I don't monitor this forum as closely as the Gossamer Links Discussion forum. We try spending as much time as we can answering posts on the forum, but we sometimes get bogged down with other projects and product development. If you don't get a response, bump your thread up, or try e-mailing support.
To answer your question, it's easy to let users add links to multiple categories with Gossamer Links 3.x (a little more work in 2.x). All you need to do, is edit your include_form.html and change:
Code:
<select id="CatLinks.CategoryID" name="CatLinks.CategoryID">
to
Code:
<select id="CatLinks.CategoryID" name="CatLinks.CategoryID" multiple="multiple" size="5">
And also make sure you have the db_gen_category_list turned on. Note that it won't work too well if you have a
lot of categories since the generated html will be very large. Also not that payments are not supported when allowing your users to insert links into multiple categories.
As to limiting the number of categories - that is not possible to do with the default program, but you can write a plugin to hook into user_add_link to perform a check before the link is added.
Adrian