The Firefox button isn't available on Mac, because the Menu Bar is part of the Mac operating system.

The orange Firefox button (it is brown on Ubuntu) is a new feature added in Firefox 4 to replace the Menu Bar. It takes the most common functions and puts them in one menu. When you maximize the Firefox window, your tabs will appear beside the Firefox button, leaving more room for everything else. This article describes how to enable it if you don't see it.

Why don't I see it?

To make Firefox look like other Windows XP programs, the Menu Bar is displayed instead of the Firefox button, while, on Windows Vista and Windows 7, the Firefox button is displayed by default.To make Firefox look like other Linux applications, the Menu Bar is displayed instead of the Firefox button.

How to get it?

Simple! Just turn off the Menu Bar! Here's how:

• Right-click on an empty section of the Tab Strip and uncheck Menu Bar in the pop-up menu.
  
  

I've tried it and I want to go back

If you prefer the Menu Bar, just turn the Menu Bar back on.

• Right-click on an empty section of the Tab Strip and check Menu Bar in the pop-up menu.