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TreeTabsNew - a browser extension for Opera and Firefox

The original TreeTabs (TT) was abandoned for over a year, so I cloned it into TreeTabs2 (TT2).

After spending hundreds of hours on TT2, the original author of TT reappeared. He had already modified his local version of TT, so most of my TT2 changes are now moot.

The license for TT does not allow collaboration, so I can no longer develop TT2. Although I thought the original author was going to modify that license, I am tired of wating for that to happen.

Since the author of TT is too unresponsive for my tastes, I will be developing my own TreeTabsNew.

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  1. This extension breaks Ctrl-Tab - the browser no longer recognizes the MRU order
  2. Because of the previous issue, using Crtl-W to close the current tab activates a random tab, often in a completely different group
  3. “After closing active tab, activate tab below if on the same level” doesn't work well with Gesturefy
  4. Restore/import group misses local file tabs
    1. Firefox/Mozilla won't allow this for security reasons. I'll have to design a workaround. (See the ToDo list below)
  5. Drag & Drop (D&D) into folder stops working after a bunch of D&D's
  6. D&D a large list of search results into a group doesn't move all of the selected tabs (5-10 get left in the original group)
  7. audio icon appears on all/most tabs, instead of just the one playing audio
  8. pinned tab keeps jumping after merge FIX=reload TT
  9. In FF (maybe others), imported groups load into containers, but container colour bars don't show in the top tabs until each tab is loaded
  10. duplicate tab not loading as child when both orphan and new tab options are set
  11. tab order lost/changed when browser restarted
  12. In FF, tab titles sometimes flip-flop between 2 groups
  13. Right-click '+' doesn’t expand folder OR scroll to active tab
  14. load tab in folder by clicking top tab makes the tab disappear - then, when TT2 reloads, the tab has been moved out of the folder to bottom of the group

These are not necessarily in order of preference or popularity (or complexity!)

  1. Autosave
    1. Session (tabs, groups, etc)
    2. Settings
    3. Allow saving to Google Drive, OneDrive, etc.
  2. Colors
    1. Tabs
      1. Active
      2. Unloaded
      3. Selected
      4. mouseover
      5. search results
      6. etc.
    2. Folders
      1. Empty folders
      2. folder background & title
      3. Custom colors for the close buttons
    3. Automatic different color for each tree
    4. Color/formatting for unread tabs
    5. add “-webkit-gradient” support
  3. CSS, allow custom CSS
    1. i.e., allow users to add custom styling rules
  4. Documentation
  5. Folders
    1. Drag & Drop (D&D)
    2. Rename
  6. Groups
    1. Drag & Drop (D&D)
    2. Rename
    3. Add keybindings for switching between Tab-Groups
  7. Import/Export
    1. Save/Restore settings (both prefs and colors)
    2. specify container for import group or session
    3. Include local links/files in Import/Export
      1. Firefox/Mozilla won't allow this for security reasons. I'll have to design a workaround where the restored page contains a link that you have to click on to retrieve the local file.
  8. Menu, context menu (aka, the right-click menu)
    1. Add settings to customize context menu
      1. Users should be able to turn off individual menu items
  9. Misc
    1. Better documentation
    2. Add hotkeys, such as to switch between tab groups
    3. Allow the vertical group bar to auto-hide
    4. Sync across computers
    5. Add confirmation prompt to Close Other
    6. Fix Ctrl-Tab so it recognizes groups and folders
    7. D&D to/from bookmark bar
    8. Allow custom font for tab titles
  10. Options/Settings/Features
    1. Move all of the features that are hidden behind buttons so they are on one page
  11. Pinned tabs
    1. add option to disable unload for pinned tabs
  12. Regex moves
    1. Add button/option/preference to make the “regex” move happen immediately
    2. Add preference to control where the “regex” move happens from (all tabs, only new, ungrouped only, only selected)
  13. Search
    1. Allow the search function to only display matching tabs (instead of highlighting them)
  14. Tab clicks
    1. Click on active tab to switch to previously active tab
    2. Add “duplicate tab” as a double-click option
    3. Add triple-click settings
  15. Tab misc
    1. Add Close Above (with confirmation prompt)
    2. Add Close Below (with confirmation prompt)
    3. have the “Undo Closed Tab” function place the tab back in the tree where it was when closed
    4. purge duplicate tabs
    5. Sort tabs option
  16. Tree/branches
    1. Add graphics for tree “limbs”
    2. Auto-expand tree when selecting a closed parent
    3. Reload/Wake Tree/Branch option
  17. Updates
    1. Enable auto-update
Although TreeTabs2 (TT2) is a fork of the original TreeTabs, it is still a “new” extension/add-in to your web browser. That means you will lose your existing TT settings when you switch to TT2.
Your tabs, groups, and folders can be saved by exporting them from your existing TreeTabs, and then importing into TT2.
To report bugs with TT2 (even old bugs that existed in the original TT), you can describe the issue in a comment at the bottom of this page.

For intermittent bugs, or for bugs that I can't reproduce, I'll need a debug log. You can enable logging via checkboxes at the bottom of the TT2 settings page. The next time the bug happens, go back to the settings page right away and click the Export Log button that's below those checkboxes. That button will create a TreeTabs2-###.log file in your Downloads folder. Zip that file, then sent it to me at tom <at> thomasmca <dot> com.

TreeTabs2 for Firefox

[n/a: No match]

TreeTabs2 for Opera

[n/a: No match]

TreeTabs2 for Vivaldi

[n/a: No match]


Egor Chistaykov, 2020/03/31 01:27

Opera now have Workspaces. I love the idea, because I can now make the top row less cluttered, but it doesn't work right with TreeTabs. When you click the side tab, it should open proper workspace but it does not. Are you going to tackle it anywhere soon? And thanks for raising the flag, we need it.

piecevcake, 2020/03/31 16:32, 2020/04/02 17:10

Hi, brilliant feature in tree style tabs, would it be hard to implement in your version?

.tab.unread .label-content {
  font-style: italic;
  1. When tab in a folder was loaded by clicking the top tab, it disappeared. When TT2 was reloaded, the tab was moved out of the folder to the bottom of the group. (new and orphan tabs are set to open as child of active tab=at the top of the hierarchy.
  2. Could formatting of unread tabs be added as a line in themes?
  3. add duplicate tab option to “triple click on tab” setting
  4. Purge duplicate tabs
  5. specify container for import group or session (useful for old TT exports)
  6. Themes
    • “Folder icon on mouse hover” is redundant and doesn't work . (I use custom tab border colour for hover, which applies also to folder tabs) - could this line be changed to “Empty folder” colour? (Separated out of “closed or empty” setting) - need to identify empty folders, esp where tabs not restoring in correct locations after restart!
Tom, 2020/03/31 19:43

@Egor, Groups in TT2 are very similar to Workspaces, so I haven't looked into Workspaces too much. However, I can add Workspace-integration to the Feature Request list.

@piecevcake, custom CSS is already on the Feature Request list. Regarding the folder/tab bug, that doesn't happen in my development version, so it should be fixed in the next release.

piecevcake, 2020/04/02 14:52, 2020/04/02 17:48

Sorry to deluge - last comments! Re wish list- (Firefox) Purge duplicate tabs: Conex does this and shows them by container - therefore not essential in TT2 (Conex also opens new tabs in active container) maybe you could just recommend using that? All tabs helper has dups and also bigger recycle stack.

ShiftControl_T seems to open tabs in original TT locations )).

Addition to wish list- specify container for import group or session (useful for old TT exports) Cheers, Vicki

PS (Firefox) Conex and all tabs helper both also have search all windows, so existing TT search is quite useful to search only in the active group.

piecevcake, 2020/04/02 15:25

Wish list +: Firefox


- “Folder icon on mouse hover” is redundant and doesn't work . (I use custom tab border colour for hover, which applies also to folder tabs) - could this line be changed to “Empty folder” colour? (Separated out of “closed or empty” setting) - need to identify empty folders, esp where tabs not restoring in correct locations after restart!

-I would be happy to contribute my custom theme to the available themes if I knew how :)

Tim, 2020/05/27 15:38

Adding myself here to get updates. I just started using Tree Tabs 1 and although I'm very pleased with how much more efficient my workflow is, there were a few things missing, for instance, container support and the search bar automatically focusing upon clicking the tab icon. So it was disappointing to see the project appeared to be abandoned but I came across the 'Are you back, Karol' issue and landed here. I just wish I had gotten a chance to try out TreeTabs2 before it got removed.

Thanks for your efforts

piecevcake, 2020/06/06 21:22

Hi Tom, We're heartened that you haven't abandoned the abandoned TT. (The original is still working far netter than the other addons, for me.)

I worked out a workaround using bookmarks addons, for 2 missing features of TT: accessing individual tabs in saved groups, and containers (both in Sidebery, but I cant work with the interface). Will email separately, have a look and see if any ideas you can use.

A thought about the random rearrangements and missing moves - ReTitle dev pointed out that rename tabs is no longer working due to FF changing tab ids between sessions… is this related?

Egor Chistyakov, 2020/06/16 20:20

I can't see in the list of features for TreeTabsNew, but I'd like to have a Rename/Mark Tab option. Sometimes I need to mark a tab /and/or make a note about it.

Andriy, 2020/04/01 03:58

Hi Tom, thanks for all of your efforts on this ! I've found this page after starting having issue with original Tree Tabs, where it loses and messed up all tree structure after browser restart. I've tried version 2.0.9 with firefox and find another issue, which (besides other things) prevents selecting multiple tabs. It looks like so if I select some tab in Tree Tab, firefox toggle to that tab, but TT tree continue to show the bottom-most tab as “selected” (with different color). Should you have a moment, could you, please, look at it ?

Tom, 2020/04/01 14:07

@Markus, you can hibernate a tree/branch by right-clicking on it and selecting Unload tree. You can wake/unhibernate an individual tab by right-clicking and select Reload. A ToDo item has been added to enable that for a branch.

@Kostas, the “new tab” process is supposed to use the setting from your browser. Change that to, and TT2 shoud use that value.

@Rizz, the “Show groups toolbar in new windows” setting removes the vertical group bar, giving you more screen space. But it only does that after enabling the setting and then opening a new browser window.

Tom, 2020/04/02 18:24

@piecevcake, your wish list and bug reports have been added to the master lists above.

Regarding themes, if you send me your customized theme file, I'll add it to the theme folder on this site.

Regarding tweaking this extension, most changes require changing code in 5 or 6 places, not 1 or 2. The “web page” for the extension is just a bunch of spans (<span>...</span>) and divs (<div>...</div>) that have no actual content. The content is built entirely using JavaScript.

Martí, 2020/04/03 00:51

Hi Tom!

I wanted to know if it is available for the new browser opera gx LVL 1 (core: 67.0.3575.130)

Thank you very much, Martí

Markus, 2020/04/03 01:06

Tom: in regards to “Unload”ing tabs → yes, that works (although the sidebar doesn't represent it by changing the colors as defined in the theme). BUT it's imho not really usefull: a) this only works for the current session; it's not saved, so next time I start the browser, those unloaded tabs will be loaded just like the others → doesn't save startup time or ram b) it doesn't “declutter” the browser, as those tabs are still… visible, albeit inactive

→ that's why Sidewise's “Hibernate” would be a MUCH better solution

You would need to save the tabs' state and close it in the browser. So it's only “visible” in TT2. You can then again un-hibernate it and it'll get loaded back in the browser itself. I know a bit on how to do that myself, but what I could gather was: TT2 always stays in sync with the browser or TT2 doesn't have it's own Tab-“Cache” if you will → this means if I close the tab in the browser via TT2 script, I cannot currently retain it in TT2 itself, as it'll get closed too…

English is not my mothertongue, so I hope you can deduce what I mean :-)

Tom, 2020/04/03 03:18

@Martí, HTG says Opera GX can install extensions.

Tom, 2020/04/03 20:18

Tom , thanks for the continued development, there is much to look forward to. So I knocked my wireless mouse off the table, it fell on my lap and who knows what clicked on what, but bang I lost all my tabs. Well I figured that , no problem, I'll just go import and them whoops, I havent clicked on export session in a few weeks. So I lost quite a few tabs that I cant remember what they were. I guess they are gone forever. Anyhow, my request would be to setup some way to autosave - export session - like once every 2 hours? or once per day?

Anyhow, love TT2 - its awesome!

Top Cat Tom

Tom, 2020/04/04 01:02

@Top Cat Tom, TT2 does have an autosave feature, but it's almost useless. It only saves every 30 minutes. By the time a user has asked for help, that's been overwritten dozens or hundreds of times. Redesigning that is on my ever-growing ToDo list. :-)

byh, 2020/04/09 04:12

Hello, Thanks for continuing development of Tree Tabs. Tree tabs stopped refreshing in sidebar in Firefox 75.0 (64-bit) (e.g. active tab highlight is not changing when I activate different tab). I need to reopen sidebar to see any changes. I have similar issue with Tree Tabs 1 (this is the reason why I'm looking for alternatives ;)) Thanks!

Tom, 2020/04/10 23:04

@byh, that's fixed in my development version. I'm not going to release it until I also fix the favicons on restores/imports. Hopefully it will be ready this weekend.

BTW, if I ever stop posting updates to this blog, it's because the coronavirus got me. I have asthma, so if I get that damn virus, I'm a goner for sure. And my wife has heart disease. So if either one of us gets it, we're both dead.

Markus, 2020/04/13 22:46

Well, good luck and stay safe :-)

Luke, 2020/05/02 13:45


First of all, I wanted to thank you for having taken the time to develop TT2 after the original developer has disappeared. Tree Tabs is most probably my most important addon and the main reason I didn't switch to Chromium. I looked forward to the stable version release and was going to download it once it was uploaded to the AMO website.

It's too bad that you had to put the development on hold. I tried to look what is up with kroppy since you claimed he has resurfaced but I found nowhere any new kind of sign of life from him. I searched on his Gitlab's profile, the addons markets (Firefox, Vivaldi, Opera) and Twitter, but there is nothing new since last year…

Tom, 2020/05/03 08:51

Luke, somebody in Europe found his LinkedIn profile, and messaged him through that. I think Karol/kroppy is in Italy, and the Italian results don't appear (by default) for U.S. users, which is why we couldn't find him. At least, that's the only explanation I can think of.

Norb, 2020/05/03 17:21

Hi Tom,

I hope you're safe and sound. I really like your addon and to be honest I am not sure why did you have to remove it. There are numerous projects with forks around. You have made the situation clear, you could team up with the original author and create a common branch or just wait where his will go, but until this happens I'd really appreciate if we could use your extension. At the moment we don't have anything and the situation is worse than a month ago. His gitlab was updated a year ago. Not sure what's going on, but I am sure it's not good for the users.

I really hope you can put yours back. Thank you.

Tom, 2020/05/04 07:24

Hi all,

I have some more testing to do before TT2 can be released. It's close, honest. :-) The license for TT does not allow releasing modified versions, so my hands are tied. I assumed that such rules did not apply to long-abandoned projects, which is why I cloned TT into TT2. Karol said he was going to change the license to allow collaboration, so I have to give him time to do that.

John, 2020/05/11 07:23

Hi Tom,

Don't have much to add, but would like to add my voice to the bunch and mention that I'm also looking forward this situation being resolved and having access to your great extension again. Stay safe!

but why, 2020/05/11 14:25


  Really? Users can customize the TreeTabs toolbar? How do they do that? 

Sorry I took so long to reply, but what I was talking about was the ability to hide or show the toolbar buttons that are already available (settings image). I don't remember the default state the toolbar buttons are in, but that user might have had the 'groups' toolbar button hidden. If you don't have it hidden, it has the option to hide/show the 'groups toolbar', a.k.a. the vertical groups bar (toolbar image).

I also never reported that bug I wanted to, so I'll do that now. It happens when I'm using the search tabs toolbar button to highlight a large number of tabs for movement, when I drag the highlighted tabs to a folder or another group to move them there some of them will not complete the movement and become deselected. For example, say I have 200 youtube tabs open and I'd type “” in the search function to highlight them, once I drag and drop them into a youtube folder most of them will move into the folder but a small amount such as 5 to 10 of them will stay outside of the folder and become deselected. The only way to get those broken tabs to move is to select them individually, they will not move as a group selection even if I control click them. Something about those broken tabs makes them not want to interact with any group selections no matter what. This appears to happen completely randomly to some tabs since I've never been able to recognize any sort of pattern to it, it doesn't matter if they are unloaded or not. I don't really have any other clues for recreating the problem, maybe you can figure it out.

Oh yeah, I also had a feature request. The original Tree Tabs had a modification made by someone to change the vertical groups bar into a horizontal one. I was never able to use it since it only worked on Vivaldi, but I would love it if you could add a horizontal groups bar to Tree Tabs 2 that worked on all browsers. Here's the link to the mod for the original Tree Tabs if you want to check it out (gitlab link).

Viktor, 2020/05/11 19:00

I do not find new commit from “original author” at github and Chrome Store. One years ago, two years ago… What is happening at all?

Tom, 2020/05/12 15:13

Hi all,

Karol, the original author of TreeTabs, has contacted me directly. He has already rewritten part of TreeTabs, and is considering which of my modifications to include in his new version. Since he hasn't posted his code on gitlab, we can't collaborate on the process. Sorry, but we're all in the same boat, waiting for him.

Markus, 2020/05/12 21:41

Hi Tom, that kinda sucks… first he does nothing for forever and now that an awesome dev (you^^) tries to maintain and improve, he springs back into existence… I mean, if he really will be actively supporting AND enhancing his addon, then ok. I guess we'll see :-\

(Is there any way for us to post feature requests to him? Is he monitoring his page on Addons.Opera?)

Thanks for your work so far, cheers!

Tom, 2020/05/15 10:58, 2020/05/15 11:16

Markus, bugs and feature requests for TreeTabs can be posted here. However, Karol hasn't responded there in over a year.

For now, it might be better to continue posting feature requests here (but check the existing list at the top of this page first).

Viktor, 2020/05/16 18:04

To paraphrase the Chinese sellers from Aliexpress - Please be patient, in near future you'll see new, improved TreeTabs. Someday, somewhere…

Markus, 2020/05/16 22:15

Well, this might be a longshot, but having seen Karol's code, wouldn't it be easier for you to write your own TreeTabsNew addon? Just a thought… :P

Tom, 2020/05/17 02:07

Actually, Markus, I kinda like that idea.

Viktor, 2020/05/17 09:22

First problem. 0) I open Vivaldi - all groups have disappeared. 1) I load a previously saved session (* .tt_session file) - all groups are restored. 2) Restart Vivaldi - Go To 0

I tried to find a file in which TreeTabs2 saves the session (possibly problems with NTFS-permissions) and could not find it yet. I ask for your help. Thank.

Viktor, 2020/05/17 09:33

The problem with disappearing groups is fixed by rollback to Vivaldi: 2.10.1745.26 (Stable channel) (32 bits) Apparently updates are far from always useful …

Tom, 2020/05/17 14:57

Hi Viktor. As you can see from the content at the top of this page, I gave up on TreeTabs2. I will be creating TreeTabsNew from scratch. Unfortunately, the Vivaldi (V) developers have a hostile attitude towards extensions. They want to include all extension-like features in V's native code, so they do very little to support extension developers. TreeTabsNew will be developed for Opera and Firefox, but not for V. For tab support in V, you will have to use either the built-in tab features, or wait for the author of TreeTabs to release an update.

Viktor, 2020/05/18 04:53

Hi Tom. Mentioning the updates I meant Vivaldi. I did not have and do not have any complaints about TT2. Better is the old Vivaldi with TT2 than the new Vivaldi without it.

Markus, 2020/05/17 21:56

← This.

As much as I like what Vivaldi is trying to do, it's just not there yet. Opera still is the most feature rich browser (and ui “user-friendly, unlike FF imho).

Plus, I've never coded an addon for FF, but I'm guessing having to support two very different browsers is a lot of work and it'll probably be very hard to keep errors from spilling into the code base of one branch to the other…

Thanks & cheers!

Stephan, 2020/05/18 13:50

Hi Tom,

I used to be a loyal user of TreeTabs, and because I loved some of it's features I put up with the frequent crashes, tree distortion and all the other kinks in this software. There simply was no alternative …

But since a couple of months, there is one: Sidebery ( It does everything TreeTabs was able and so far never crashed on me (knock on wood!). The only thing it cannot do, is to display these nifty vertical tabs …

Seems like a really mess with the licenses involved (I wonder why you cannot use his code, but he can use your code …) I really appreciate your effort to get TreeTabs going again and now your effort to rewrite it. Wouldn't it be better to join forces and you make your expertise available to Max Badryzlov, the maintainer of Sidebery. In my experience he is open to suggestions and accept bug reports but might have not all the time to work on them. I believe it is always better to work on ONE project and not to waste manpower to maintain two or more very, very similar programs.

Well, just a thought. I wish you good luck, however you decide.

Jay, 2020/05/27 11:45

I look forward to TreeTabsNEW. Best of luck.

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