A couple of questions:

• How is the "switch user" step done? Where do you choose that option? Do I actually need more than one user to reproduce the issue? Does clicking "Win+L" and logging back in causes reordering, too?
• If you reset all of the tweaker's options to their default, does the reordering still happen?
• Is the issue specific to Firefox?
• Does the reordering happen only within button groups (e.g. shuffling the Firefox window), or between button groups too (e.g. shuffling the Firefox, Notepad, and Word)?

Why is it marked as a bug? Is it caused by 7+ Taskbar Tweaker, i.e. do you only see the issue when the tweaker is running?

Currently that's not possible with 7+ Taskbar Tweaker. I tried to implement this once, but it turned out clumsy and confusing.

That's possible with 7+ Taskbar Numberer. See here:

https://superuser.com/a/916838

What's the issue? Please provide more information.

Please check if that's the bug you're having:

https://tweaker.userecho.com/topics/116-thumbnails-not-displaying/#comment-779

Does the issue happen only when 7+ Taskbar Tweaker is running? What do you mean by "don't respond"? Which options are you using with 7+ Taskbar Tweaker?

It's not really related to the taskbar, so it's unlikely to be implemented by 7+ Taskbar Tweaker.

That's already possible with the Mouse Button Control advanced options. Refer to the help file, and let me know if you need help with it.

Please provide more details. Are you seeing any error message?