You can look at the Classic Theme Restorer extension to restore some functionality that was lost with the arrival of the Australis style in Firefox 29.

• Classic Theme Restorer: https://addons.mozilla.org/firefox/addon/classicthemerestorer/

See also:

• https://support.mozilla.org/kb/how-to-make-new-firefox-look-like-old-firefox

• https://support.mozilla.org/kb/common-questions-after-updating-to-new-firefox
• https://support.mozilla.org/kb/learn-more-about-the-design-of-new-firefox

Unfortunately the only option (I spent the last hour investigating this) is to uninstall version 29 and go back to version 28. The downside is that there will be no security patches for 28 moving forward. I just hope the developers see sense and stop trying to improve something that worked well in the first place.

Yes, that's what I ended up doing, going back to 28. Whew! I couldn't read 29, it was horrible. I join your wish that the developers will leave well alone.

There's still a couple of options for you (I did some further research)

If you're on a 64bit OS then you can get waterfox, which is built on firefox so it'll remain secure and you simply uninstall FF (without removing your preferences) and then install waterfox and everything will be as you left it, at least it was for me. The other option is palemoon, which I haven't looked into that much because waterfox solved my issues but it's also built on FF but has some optimizations and layout tweaks.

Hope it helps ;)