Incredible extension. Not only does it deliver on its promise of tree-organization for tabs, but it also keeps up with other Firefox features like container tabs and even tab hiding! There has clearly been a lot of love and thought put into this extension to not only make it usable, but to make it feel like a native Firefox feature instead of a third-party extension. Its customization options are fantastic too, including the much-appreciated ability to tweak its CSS. Great work all around.