It is well known that you can CMD click, or, if you have it set up so, middle click on a link in the Safari Bookmark bar to open it in a new tab. It is, however, not possible to do so with links that are inside folders on the bookmark bar. I just discovered a way around this. If you middle click on the folder and then click on the link as normal, it will open in a new tab. This may not seem like a big deal to many, but I'm sure there are some out there who were just as perplexed by this seemingly absent feature. It disrupts the use of the app to have to press CMD-T every time I want a new tab to check bookmarks, and now I don't have to! Still not sure how to do it with just the CMD button...but this works for now!