PUBLIC MARKS with tags firefox & favicon

Google Icon enhances search results by adding the favicon next to each search result (if available). Icons make it easier to recognize your favorite websites and breathe more life into that dull search page.

In the default Firefox theme (1.5 and 2.0 RC1) on a Macintosh, favicons do not show up on the Bookmarks Toolbar. Various other themes (e.g. Pinstripe for Firefox) also lack the favicons. However, other themes (e.g. Phoenity Modern) do have favicons show up on the Bookmarks Toolbar. What's toggling whether or not the favicons are showing up?