Nope, missed it.
You weren't around when I explained that I'm developing this software for a client, a private university, and using the Zone as a test site. So I have a stake in understanding what goes wrong that goes beyond just taking care of the Zone. I'm willing to take time to investigate something like this.
It was pretty easy in this case. The link button isn't an insert link button, it's a wrap the currently selected text in a link button. When the cursor's just a caret, no text selected, link button is grey; select some text and it all becomes so black and white. Click the button and a little dialog overlays for the URL and title. Viola.