Right-click on the toolbar or tab bar and select 'Customize' option. To add the 'Downloads' button back to Firefox toolbar, follow these simple steps: METHOD 1: Using Toolbar Customization Window.
Facebook for Chrome is an extension with incredibly easy access to your Facebook right from your browser toolbar. Address bar / Menu bar / Bookmarks bar missing in Firefox. Once the toolbar is emptied it will be automatically deleted from the toolbar. Now drag and drop the items from toolbar to the customize window. If you want to remove the toolbar permanently right click on the toolbar and select Customize. To learn how to further customize your menu items and toolbar preferences, visit Adobe Acrobat Workspace Basics.