In Firefox 20.0.1:
- Edit a page that has a bulleted list.
- Place the cursor on the first bullet item.
- Click the "Bullet List" button. The first bullet item loses its bullet. (Correct.)
- Click the "Bullet List" button a second time. The first bullet comes back (correct), but there is now a blank line displayed below it.
Similarly, if you remove & add a bullet in the middle of the list, you get blank lines above AND below the item.
Similarly, if you do this with a numbered list, the blank line breaks the numbering: the list items below the blank line start over from "1".