when bookmarks button is removed, add a "bookmarks" sub-menu to the firefox button (similar to the "history" sub-menu)

The bookmarks menu is going to be in the Firefox button anyway. http://blog.mozilla.com/faaborg/2010/07/18/details-about-the-firefox-button/

Hence Please rename the bug to become Add Bookmarks Sub-Menu to Firefox Button

I'm duping this change forward to bug 583386 so that we can centralize discussion, work, and blocking status for beta 4. Slight change: the bookmarks command will appear in the menu either way, regardless of if the toolbar button is being used (many other sub-menus in the Firefox menu will have optional toolbar buttons, and it would be odd for all of them to control which of two places they appear).