Tooltips break some links

Sometimes Thunderbird thinks that the modified link text (with the tooltip) is showing a link, and warns the user when they click on it, asking if they want to visit the "displayed" link. This will not work, because the "displayed" link isn't actually a link, but an amalgamation of a link and whatever text was originally there.

Modify the tooltip so it ideally doesn't trigger Thunderbird or use a Javascript-based tooltip so the original DOM doesn't need to be modified (excapt for adding event handlers, of course).