[problem] With Middle-Click closes tab extension - clicking on the scrollbar also closes tab

[MrAccident]

It's not being Technical ― it's many years of Experience with the Computah.

[moonbat]

You have to replace the file inside the original XPI, not create a new XPI.

No, you can create a fresh XPI but you should not include the containing folder when zipping it up. If you open your zip file in any zip program, the first thing you see should be the top level contents of the extension (install.rdf, chrome.manifest and other files), and not the parent folder that it was in.

[MrAccident]

No, you can create a fresh XPI but you should not include the containing folder when zipping it up.

I found this answer somewhere, before finding the method that worked for me, and tried it using PackIt ― and it didn't work for me. So something is still missing there.

[moonbat]

See that you're creating a zip file and not something else that can't be opened, in addition to making sure the file structure inside is correct as I mentioned.