Do you like Firefox 4? If you upgraded from Firefox 3.6.x to Firefox 4 one element you may not like in Firefox UI is orange Firefox button. Firefox buttons offers two-tier menu with more of same options shown in classic Menu bar. You can still hit “Alt” button on keyboard to bring up Menu bar temporarily. Looking for a way to permanently remove orange Firefox button there is an add-on for that called App Button Remove.
App Button Remove add-on for Firefox 4 removes orange Firefox menu button permanently and no restart is required to install this add-on (restartless add-on). Install the add-on, Firefox button disappears you can access the menu bar from then onwards by Pressing Alt>Toolbars and selecting Menu bar.
To get the Firefox button back simply disable or uninstall the add-on. There is also an extension from same developer to change the color of Firefox button which is available from here (App button color).