Wikipedia:Wikipedia Toolbar

Wikipedia Toolbar is an add-on (extension) for Mozilla Firefox. It speeds up Wikipedia navigation by making the most common Wikipedia page functions always accessible from a fixed location in your browser window. This eliminates the need to scroll around the pages themselves in order to find and click on navigational links.

Wikipedia Toolbar is only (currently) available for use with the English version of Wikipedia, and only for Mozilla Firefox. You may leave feedback or questions via the talk page. Note however that this software is no longer being actively developed.

Features

 * Most of the navigational elements that appear standard across Wikipedia pages are available from the toolbar, i.e. the search bar, watchlist link, page history link, and edit link, to name a few. There's also a toggle button for switching between a page and its associated talk page.
 * Some buttons correspond to "hidden" page functions on Wikipedia, namely the "purge server cache" and "no redirect" functions.
 * This toolbar comes with a toggle button, so it can be easily hidden away when not in use, and brought into view when needed.

Limitations

 * Does not work with Firefox 5.0.
 * Not available for Firefox 21.0.

Usage notes

 * All buttons in the toolbar can be middle-clicked to open their function in a new tab.
 * Some buttons in the toolbar may only function when logged-in to a Wikipedia account, even though they may appear clickable when not logged in. These include watchlist, watch and unwatch, as well as all links in the "my" menu.
 * Hold the mouse cursor over a button to see a tooltip describing its function.

Status
Wikipedia Toolbar is in the beta stage. It is fully working, but may contain bugs.
 * Latest version:  (last updated 18:28, 22 October 2008 (UTC))
 * See version history

System requirements
The only requirement is any Mozilla Firefox version from 1.5 to 3.7a2pre .

Download location

 * Wikipedia Toolbar at Mozilla Addons

Instructions
Just visit the link above and click the install link.

Toolbar toggle button
After installation is complete, you can optionally add the toolbar toggle button to your standard navigation bar. You can use this button to quickly hide or show the Wikipedia toolbar.
 * 1) Right-click in your standard Firefox navigation bar (where the back/forward buttons are) and click "Customize".
 * 2) Drag the button labeled "Wikipedia Toolbar" to the location of your choice. Click "Done".

''Note: Due to a bug, the toggle button's graphics may appear garbled while in the "Customize" window on some systems. Don't worry though -- the correct button graphic (Wikipedia globe logo) will display correctly after placement in the navigation bar.''

License
There is none. Wikipedia Toolbar is open-source software. You're free to use, distribute and modify it.

Source code
To view the source code, simply download the installation file (save it, rather than installing it) and replace the "XPI" extension with "ZIP", then extract its contents. Like most Firefox extensions, this one is written in XUL and Javascript.