A safe, stable beta supporting TB v115.
This version supports v115, except for missing the toolbar menubutton. You will need to use the Tools menu, or the context menu on the folders you've selected, to start a duplicate message search. The comparison criteria can be configured only from the extension's options dialog in "Tools | Add-ons & Themes".
Q: Why are you releasing a beta version?
A: A proper version would require the toolbar button to work, but it's currently broken. Otherwise this would a non-beta release.
Q: Why is the menubutton gone?
A: In the course of the transition to v115, the Thunderbird developers removed the application toolbar in favor of a new "unified toolbar". Unfortunately, they did not document how regular chrome, like this extension, one can add new elements to that toolbar; and it's rather tricky, because its contents deleted and re-generated frequently, so that "just" straightforward adding the button doesn't work.
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Other than the compatibility change, additional improvements in this version are:
* Now setting the completion percentage indicators or the "meteros" effect in the status bar during different stages of processing, indicating progress.
* More consistent reporting of what's occurring right now in the status bar, including clearing it when the search is done.
For more information, see:
https://github.com/eyalroz/removedupes/releases/tag/v0.5.4b5