This addon introduces attributes to comments allowing the comments to be organised into an hierarchy, i.e. a tree, or threaded (though I'm reluctant to use that word due to the way "threads" tend to be implemented in other discussion boards).
Links have been introduced on the comments screens allowing a user to reply to a specific existing comment. This then adds the new comment as a child of the existing comment.
Comments are displayed in tree order. Comments are indented according to the depth they are in the tree. The depth is only calculated for the comments displayed on a single screen, and not for the whole discussion, so pages with a larger number of comments displayed will show the structure to better effect.
The changes the plugin makes to the database involve adding three additional columns to the comments table. Otherwise, nothing else in the database is changed.
The comments are ordered into their trees or threads when the module is installed. If the module is removed, ordering returns to the default posting date order, so it is safe to install and uninstall if you find you don't like it. Because the comment ordering is important, some other plugins that order comments (e.g. some of the voting plugins) may clash with this plugin and give some undefined results.
Please note there is a single line that needs to be added to your theme for the visual indenting to work. The "readme.txt" file provides details on how to do this. We hope that in future versions of Vanilla, this will not be a necessary step, but up to at least version 2.0.14, the line must be added.
Note: This addon is not compatible with any other addon that alters the order of comments, such as the voting addon used on this site. There is unlikely to be a way to make them compatible, but I'm open to suggestions on how it could work.