I’ve been using Tab Mix Plus to display multiple tab bars all this time and with the help of “Disable Tabs on Top” extension I found a couple days ago I moved the tab bar below the address bar. I liked with the new look but then decided to try this Tree Style Tab after seeing a Firefox screenshot captured by one of Reddit users. It’s a Firefox extension that move tabs to the side. I’ve known this add-on before but wasn’t interested until I saw that snapshot.
Tree Style Tab moves Firefox tabs to the side as soon as you install the extension and restart the browser. The default location is the left side but you can move it to the right by configuring the add-on via its Options panel. One of the prominent things that you will be able to notice immediately is that any link that you open from a webpage becomes its child, and when another webpage is opened from the child tab, the tab becomes the parent of the webpage. It’s pretty much like the structure of the folders in Windows explorer.
A new page can also be made as a child of an existing tab by clicking on that tab and then middle-clicking on the new-tab button which is placed under the tabs.
As you can see from the screenshot above, every parent and subparent tab has its own expand/collapse button. The default setting expands the tree automatically once a parent tab gets focused and collapse automatically when you click on another parent tab. Unfortunately, this auto setting doesn’t always work in the current release so sometimes you have to do it manually. Even so, this ability to expand/collapse a tree can definitely save some space and minimize the clutter from opening lots of tabs.
If you don’t have a wide screen that fits the webpages that you open–which is marked by the appearance of the horizontal scrolling bar–after you move the tabs to the side, you can enable the option to auto shrink or even auto hide the sidebar. The show-tab delay can be configured according to your liking.
Version tested: Tree Style Tab 0.14.2013052901
All in all, this extension doesn’t only let you move Firefox tabs to the side but it also provides a large number of options to customize the look and to change the way it works.