Stiern has a great and really thoughtful piece about how we denote linking in CMS (and elsewhere around the web). The ubiquitous linking chain has been proven over and over to not be quite intuitive enough for non-geek CMS users (he outlines the study he did in the article), but no one seems quite sure what the next best thing is, that stays easy and icon-able.
For me, it’s an odd question. Because I tend towards geek, I rarely use that little button. I’m one of those weirdos who types out my HTML link tags just like I type out the rest of my sentence. This is a really interesting question for me because I absolutely never considered it, and as a designer and sometimes user experience nut, I really should.
For the record, in WordPress, I just see the word “LINK” in my interface. It works, but it doesn’t solve the icon question at all, it just avoids it. Here’s how WordPress shows CMS users what to do:
It’s mostly word-based. Is this the best approach? Anti-icons?