2.1.0

   * Better handling of restored tabs.
   * Better handling of new tab opened by Ctrl-T.
   * Redirect legacy `about:treestyletab-group` URI to new `moz-exteions://...` URL.
   * Don't break tree when a member tab of the last tree is promoted by dropping below a paranet tab.
   * Detect copy action for dragging correctly. (regression)
   * Detect sidebar's open/close status more correctly again. (regression)
   * Open tab as independent correctly based on configurations, for duplicated tabs.
   * Move descendant tabs to the new window also by the "Move to New Window" command.
   * Disallow to drop tab onto scrollbar.
   * Keep tabs discarded after moved by "Move to New Window".
   * Move tree to new window more safely from fake context menu.
   * Close only right (below) tabs in the window correctly.
   * Specify background color for dummy group tab.
   * Accept tab ids changed by moving between windows, for API's input.

2.0.7

Better tree restoration for restored sessions.

2.0.6

   * Allow to open new active child tab under a parent tab which is internally collapsed. (regression on 2.0.3)
   * Restore collapsed/expanded state of tree after crash recovery, if possible.
   * `tabs.Tab.openerTabId` of each tab is now updated based on tree structure, for other addons.
   * Tabs with updated `tabs.Tab.openerTabId` are now automatically attached to the opener's tree. (Due to [the bug 1409262](https://bugzilla.mozilla.org/show_bug.cgi?id=1409262 "1409262 - Updated openerTabId is not notified via tabs.onUpdated if it is changed by tabs.update()"), updated relation is not applied immediately.)
   * Scroll to the focused tab correctly, when it is focued by Firefox's `browser.tabs.selectOwnerOnClose` feature.

2.0.5

   * Restore tree for tabs restored from crash, if possible.
   * The tab bar is scrolled to newly attached child tab prior to its parent, if the parent is already out of the viewport.
   * Animation effect for completely loaded tab won't be applied again and again for already loaded tabs anymore.
   * Clicking on the tab bar itself is now cancelable by other addons. If any addon returns `true` for the notified message with the type `tabbar-clicked`, TST's default behavior (open new tab) is canceled.
   * Apply macOS specific behavior on macOS correctly.

2.0.4

   * The current tab is never scrolled out when a new tab is opened and the tab bar turned to "overflow" mode.
   * Never show blue gradient for notification when the window is resized.

2.0.3

   * Tree structure is restored when Firefox is started with some extra URLs (or files.)
   * Sidebar UI is now rendered with the system font for message boxes (same to Firefox's tabs).
   * "Max level of indentation" config works more correctly (including `0` case.)
   * Focus redirection for closing current tab works more correctly.
   * "Close Other Tabs" command in the fake context menu don't close pinned tabs anymore.
   * Click actions on fake context menu items now work only on certain correct cases.
   * The fake context menu is shown on the correct timing same to native context menu on the platform.
   * Last scroll position of the tab bar is now restored.
   * TST sidebar's initialization process is optimized and now it is opened more quickly.
   * Add a new option to activate behaviors around tree when TST's sidebar is not shwon. The option is activated by default now.
   * Tabs opened at startup (like "Home" with multiple URLs) aren't grouped anymroe. The maximum delay to detect "opened on startup" is customizable and it is 500msec by default.
   * Sound indicator icon is correctly updated for changes. (regression on 2.0.2)
   * "New Tab" button in the sidebar opens new next sibling tab correctly (if you configured).
   * Collapse/expand tree by changing focus and closing current tab more correctly.
   * Collapsed/expanded state of tree is restored more correctly.
   * Infinitely animation throbbers are gone.
   * Restore closed tabs with previous tree strucutre more correctly.
   * Restoring of closed duplicated tabs unexpectedly broke tree structure.
   * Too narrow height of tabs is corrected for the "Metal" theme.
   * Tabs moved next to collapsed tree by Firefox or other addons won't be attached to the collapsed tree anymore.
   * Invalid middle click (the mouse is moved out before mouseup) is correctly ignored for "close the tab" on a tab and "open new tab" on blank area.
   * Focusing and positioning of duplicated/restored tabs are processed more correctly.
   * Ghost tabs won't be produced anymore from tabs closed after opened immediately.
   * Select tab immediately when mousedown event is fired on a tab, like legacy TST.
   * Use more suitable term "end" instead of "last" for labels of some configurations.
   * New tabs opened at the end of the tab bar is now completely shown (if possible) when the tab bar turns into "overflow" mode by the opened tab.
   * [Simple `ping` API](https://github.com/piroor/treestyletab/wiki/API-for-other-addons#uninit-special-features-for-tst-when-tst-is-going-to-be-disabled) to check TST's living status from other addons is now available.
   * Tabs gotten with [`get-tree` API](https://github.com/piroor/treestyletab/wiki/API-for-other-addons#get-tree-information) now have correct `active` status.

2.0.2

   * Open new tab by middle click on the blank area, like Firefox does.
   * Synchronize animation of throbbers, like Firefox does.
   * Apply "burst" animation for completely loaded tabs, like Firefox does.
   * Show fake context menu with the system font for menu items.
   * Process fake context menu commands correctly when the menu is opened on non-tab area.
   * Fix invisible throbber on active tab with some themes.
   * Open new tab as next sibling without breaking tree, when the current tab is a root tab.
   * Group tabs by a dummy tab correctly on secondary and later windows.
   * Don't open needless group tab in a rest window when another window is closed.
   * Don't highlight unread pinned tabs when they are not faviconized.
   * Respect Frirefox's behavior of `browser.tabs.selectOwnerOnClose` more correctly. Now the "owner" tab is focused when the current tab is closed. You need to disable the option via `about:config` if you hope TST to control focusing of tabs completely.
   * Don't create recursively grouped tabs from newly opened tabs.
   * [New APIs to override the wheel scrolling behavior](https://github.com/piroor/treestyletab/wiki/API-for-other-addons#override-reaction-for-mouse-wheel-rotation-on-the-vertical-tab-bar) are now available.
   * Updated zh-CN locale by YFdyh000, thanks!

2.0.1

   * "Middle click to close tab" behavior becomes same to Firefox's one (closed on mouseup).
   * "Dragging" appearance of tabs are correctly cleared when the dragging is canceled.
   * Tabs were too easily detached from the window by drag and drop of a tab onto itself. Now dropping of a tab onto itself is simply ignored.
   * Fix missing translation in Japanese locale.
   * Fix too large padding in tabs in the "Sidebar" theme (by Niklas Hambüchen. Thanks!)
   * The option to control positioning of tabs opened by "New Tab" command is now applied for tabs opened by keyboard shortcut Ctrl-T (⌘-T), if they are opened with the URL "about:newtab". (But there are some problems. [See also technical details.](https://github.com/piroor/treestyletab/issues/1038#issuecomment-332711522))
   * "Open as next sibling" choice for options to control new tab position works more correctly.
   * Focusing of tabs is controlled more correctly for closing current tab.
   * "Move Tab to New Window" in the sidebar context menu works correctly.
   * Reduce CPU usage for throbber animation.
   * WhatsApp Web tabs were unexpectedly eats CPU resource.
   * Last effective icons are restored correctly after restart, for some websites including WhatsApp Web.
   * Tabs are updated more correctly by events. For example, view-source tabs are shown with correct title more certainly.
   * Restore tree structure when a parent tab is restored after it was replaced with a group tab.
   * All collapsed descendant tabs are now shown in the tooltip.
   * An announcement message is shown automatically, when TST is updated from legacy version to 2.x or later.
   * Now pinned tabs are easily unfaviconized. (A new checkbox is added in TST's configurations.)

2.0

   * Rebuilt on WebExtensions.

0.19.2017090601

   * Tree Style Tab's configurations and tree information are now exportable, as a migration assistance for Firefox 57 and later. See the "Advanced" section in the configuration dialog.
   * Tree restoration on the startup or restored window is just triggered by SSWindowReady now. TST don't wait SSTabRestoring event anymore.
   * Fix too frequently redrawing of the tab bar by any animation effect in Firefox's toolbar.

0.19.2017090201

   * Tab bar position is updated after visibility of a toolbar is changed with animation effect.
   * Initialize itself correctly on lately versions of Firefox.
   * Duplicated bookmarks won't be created.
   * "ru" locale is updated by Infocatcher. Thanks!
   * "fr-FR" locale is updated by AxlMun. Thanks!

0.19.2017061601

   * Works on Nightly 56.0a1.
   * Allow to drop multiple local files to the tab bar, on Firefox 52 and later.
   * Scroll to a newly opened tab if possible.
   * Load a URI in an existing tab when it is dropped into the content area. (New tabs were wrongly opened by such operations.)
   * Refresh tab bar correctly when any new notification appears.
   * Support "Compact Dark" theme on Firefox 53 and later.
   * Open tabs from middle-clicked items in "Synced Tabs" sidebar as new root tabs.
   * Support contextual tabs on Firefox 54 and later.

0.19.2017031101

   * Works on lately Firefox versions. (Tested on Nightly 55.0a1.)
   * Drop support for Firefox 51 and older versions.
   * Introduce a new choice "No control" as the position of new child tabs. If you choose the option, new child tabs from links will be opened like Firefox's default behavior.
   * Introduce a new choice "Click" as an action to show shrunken/collapsed tab bar.
   * Treat child tabs opened by the preference `browser.tabs.insertRelatedAfterCurrent`=`true` more correctly.
   * Fix broken configuration UI for the "auto hide delay".
   * The position of the tab bar is now changable again by drag and drop.
   * Collapse the dragged tree while dragging. The experimental "shrink" behavior in the previous release was removed.
   * Open new blank tab as next sibling tab correctly, even if the current tab is in a last tree.
   * Restore children tabs correctly when a parent tab is restored by "undo close tab" command.
   * Fix visual erros in the "Vertigo" skin.
   * Avoid fingerprinting by website authors.
   * Added Greek translation by Vangelis Skarmoutsos. Thanks!
   * Known issue: opened or expanded tabs sometimes stay invisible until you move the mouse cursor on it, due to [Firefox 52's bug](https://github.com/piroor/treestyletab/issues/1202). This doesn't happen on Firefox 53 and later. Simple workaround is disabling of tab animations by `browser.tabs.animate`=`false` in `about:config`.

0.18.2016111701

   * New background tabs are opened correctly. (The first opened tab was opened in the foreground unexpectedly.)
   * Shrink other dragged tabs while dragging. (experimental feature)
   * Better handling of "Tabs in Titlebar" feature of Firefox itself.
   * Open new tab as a next sibling morecorrectly.
   * Better styling of tabs with the "Metal" skin on macOS (OS X). (Many thanks to Andrew Shu! [patch 1](https://github.com/piroor/treestyletab/pull/1192), [patch 2](https://github.com/piroor/treestyletab/pull/1194))
   * Show microphone icon on Nightly 51.0a1 in pinned tabs correctly.
   * Isolate from old libraries and old unrecommended methods.

0.18.2016090802

   * Failed to initialize the browser window with a preference: `browser.tabs.drawInTitlebar`=`false` (regression on 0.18.2016090601.)

0.18.2016090801

   * The dialog to choose how tabs to be opened from a bookmark folder is now cancelable.
     (If you choose the "Cancel" button, the operation will be totally canceled and no tab will be opened.)
   * Isolate codes from `new Function()`.

0.18.2016090601

   * Isolate codes from `eval()` hack.
   * Drop support for Firefox 44 and older versions.
   * Remove compatibility codes for unsupported/unpublished/obsolete addons: Google Toolbar, Snap Links, Highlander, PermaTabs, FullerScreen, DragNDrop Toolbars, Optimoz Tweaks, Tabberwocky, Super DragAndGo, Drag de Go, FLST, Mouse Gestures Redox, Aging Tabs, Autohide, Smoothly Close Tabs, IE Tab Plus, Locationbar², DomainTab and TotalToolbar
   * Remove compatibility codes for Tab Mix Plus's custom session management system. Now it is strongly recommended you to use Firefox's built-in session management system. If you choose the TMP's session management, there is no guaranty about what happens.

0.17.2016083101

   * Fix broken tab color of Firefox 51 and later（due to [bug 1297157](https://bugzilla.mozilla.org/show_bug.cgi?id=1297157).)

0.17.2016083001

   * Better handling about positioning of new tabs duplicated by other addons.
   * Now you can drop tabs onto another tab more easily. (The drop area of each tab is enlarged.)
   * The tab bar can be shrunken even if there is something wide toolbar item like the search bar.
   * Better positioning of tabs opened from the last child tab.
   * Tabs opened from inline frames or webpages including `base` tag are attached to the current tab as new children correctly.
   * Reduce warnings from undefined CSS properties (by asamuzaK. Thanks!)
   * Supports [contextual tab coloring on Firefox 51 and later](https://blog.mozilla.org/tanvi/2016/06/16/contextual-identities-on-the-web/).
   * Remove icons from the pane switcher in the configuration dialog (because Firefox 50 and later have no suitable icon for some categories).
   * A new secret preference `extensions.treestyletab.blockTabsInTitlebar` in introduced to allow customization with userChrome.css around "tabs in titlebar" style.
   * Tabs duplicated by ctrl-drag-and-drop of a tree are duplicated with correct tree structure.
   * Reduce warnings about "unsafe CPOW usage" for the "view image" command.

0.17.2016061501

   * Scrollbar in the tab bar couldn't operated by mouse if you show the menu bar, at Firefox 47 on Windows.
   * The tab bar was wrongly fixed to "overflowed" state after you shrink the tab bar too narrow.
   * Better compatibility with the "Dark" theme of Firefox Developer Edition.
   * Better compatibility with FireGestures.
   * The width of expanded tab bar isn't enlarged too much, when shrunken tab bar is going to be wider than expanded tab bar.
   * Introduce a new secret preference `extensions.treestyletab.controlNewTabPosition` to disable new tab position control by TST itself. When you use any other addon like Tab Mix Plus which provides ability to control new tab position for bookmarks or others, you possibly get better experience with turning it to `false`.
   * The hidden tab bar is never expanded for feedback around pinned tabs.