With Firefox 4, Mozilla has introduced a new user interface, where tabs always remained on top by default, but they offered the option at that time till Firefox 15 on the Options sub menu to bring them to the bottom, that option was removed in Firefox 15, but still, we were able to disable tabs on top by changing ‘browser.tabs.onTop’ preference value to ‘false’ by visiting about:config.
How to bring tabs to bottom for Firefox Australis
Mozilla has now gone ahead and removed that about:config preference too in Australis. Now we’ve no option, but to rely on developers to offer that feature through an add-on, which is why Firefox is famous for. Fortunately, a developer has created Tabs on Bottom extension that does just that, yes! It brings tabs to bottom for Australis.
Install the extension and without restart of the browser, Australis interface will be shown with tabs on the bottom now. Remove or disable the extension to get tabs on top again.
FYI, You can revert Firefox Australis look to Classic with an add-on, which not only brings old theme for tee browser, but also lets you enable ‘Tabs not on top’ and ‘Add-on bar’ features.