Interesting! Some overlap with these Firefox add-ons: - Tree Style Tabs: https://addons.mozilla.org/en-US/firefox/addon/tree-style-tab https://addons.mozilla.o

Interesting! Some overlap with these Firefox add-ons: - Tree Style Tabs: https://addons.mozilla.org/en-US/firefox/addon/tree-style-tab https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta... (more simplistic, no session saving functionality) - Tree Tabs: https://addons.mozilla.org/en-US/firefox/addon/tree-tabs https://addons.mozilla.org/en-US/firefox/addon/tree-tabs (more complex, can also save sessions, but incompatible with some other add-ons and not evaluated for security by Mozilla) Neither rearrange tabs in the window, just offer an alternate tree listing of open tabs.