Hope you take the time to read the response.

Regarding the bugs and problems that I reported as being solved, most probably I did that because I genuinely thought that I fix them. If they are not fixed or other issues appear after a while that's something different. Please consider that Firefox nowadays makes so many updates that simply you can't control. Addon developers have 0 control over what Firefox is nowadays and everything is designed for the rest of the users... that basically may have 1-2 addon or non at all installed... and power users have been left behind somehow simply because they don't matter in the grant scheme. Now I'm not saying that things are intentionally, but all these constant updates can brake stuff... make addons resets internal settings, disable them, and so many similar things. When this happen the addon developer have done nothing wrong but most of the users blame addon developers for these kind of errors as well.

Now I'm not saying that addons are clean and there are no bugs in them. Clearly is not the case.
In my case, I know that there are some issues, but was not really able to figure them out, when and why they happen. That doesn't mean that I'm right and a particular user is wrong and the addon is perfectly fine. Not at all... it just mean that I might have a very hard time finding the actual cause of the issues.
I have several of those like it's the one your describing above:
For example certain settings may make the restoring functionality to restore everything in reverse order. I can see that, and that's why I added an option to reverse the restoring of tabs. What I can't really get to reproduce is why you say they are scrambled. I simply can't make this happen... Trust me I'm really trying, I have really no idea why and how to do that. If I could understand where it's happening I can find the root cause and fix it. But in programming usually if you're not able to reproduce something is extremely hard to fix it. I look over the code again and again and things seems fine. My only concern is not to be something internally in Firefox that somehow when I tell him... please restore 1, 2, 3 he reorders them somehow into whatever else. But I can't tell if that's true or not because I can't reproduce it. Really really sorry about it.

The addon is unmaintained and out of date. I understand why you say that but it's not really true. I care about the addon a lot, but I simply considered that most of the functionality is solid enough and things work as they are suppose to. I do have a few issues reported, and lots of features requested, but imagine that working on them it's not 1-2 hours. I'm not a bad programmer and I can work pretty fast... but things can take a lot of time. New features need to be tested well before releasing them so I have to take into consideration that. Now, here's the problem, in the last few years I simply had very little time to invest into this addon (because life). I hope you understand that getting 1, 5, 10 $ through donation (once in a while... which I mean months), it's only as a form of thank you from some people that are really happy with the product and that in reality they really can't help you invest more time into developing the addon. Free open source addons don't help you live from a month to another... so as anyone around me that has to provide for themselves, I had to prioritize my job, other projects and so on, you know things that would actually... buy you food or whatever else you may dream of (even if that's not essential). And I think that it's perfectly fine.

Sadly, I have around 2-3 updates that were kind of ready, but are only available on Github, and I was not able to release them simply because I did have time to test the new features thoroughly.

It's the addon perfect. No not at all. Does it have issues. Seems so, but depends a lot on what you do. In my case it's a core part of my daily browser experience and it's really hard for me to live without it. I use it a lot. And it does the job perfectly without any errors for years. But at the same time I don't use all the features, I rarely restore full sessions and most of the time I interact with very few of the links and save new ones and so on. But when I do restore some sessions I have not seen errors (myself again... can' tell anything about anyone else)

Is the addon out of date. I personally don't think. There are many new people that try it and they like it and for them it's really useful. So it's always based on our personal experience with thinks. I just hope that with time when I will be able to finally make a serious update to it, I will fix as many things as possible that people have been reporting lately. Also... think about it... If I have not updated it... what exactly went wrong if issues started to pop-out in the last period. Most probably Firefox did something internally with an update that may have broke something from the addon. As addon developers, we simply can't put up with that. Having so many updates that may break things and us constantly be ready to fix things when it happens :D.

I may have a different view on this than others, but I put here the addon in the hope that it would help others as much as it helps me from day to day. It's not perfect, it's not good for everyone, but it's an option for those that find it useful.

Lastly, nothing I said above it's an excuse for your bad experience with the addon. I just stated some facts as I see them. I'm sorry about all the issues that you had and just so you know I will definitely try to fix things when I know exactly what goes wrong. Right now, trust me, I really have no clue. If you can give me any hint, concrete example that I can reproduce, that would be perfect and I might be able to fix it.

Thanks for using the addon for as long as you did, have a nice day.