Access recently closed tabs (access to the session information): to save tree information of tabs (structure, collapsed/expanded state, etc.) to tabs' session information and ask to Firefox to manage them as bundled.
What Tab-Tree different from others is that Tab-Tree gives a tree-style list for tabs. This tree separates all tabs into different groups by the relationship between the child-tab and their parent-tab, which gives you a better insight for all the tabs.
Forest is built on the concept of managing tabs like a "tree". By default, any new tab opened from the current tab is organised as the "child" of the current branch and displayed beneath of the current tab in the menu.
