When I rename an .xpi to a .zip, unzip it, delete the original .xpi, re-zip the directory, and rename it to .xpi, Firefox deletes this "touched" file upon restart (nothing really changed, other than the modified date). I watch it disappear from the folder as Firefox starts. (If you set the read-only flag Firefox still deletes it.) I'm following the Mozilla guide - and it says to compress the file with "send to > compressed zip folder" and then rename it to .xpi.

I originally thought I was messing up the file, and Firefox was deleting it because it was broken. Then I just unzipped and rezipped a working plugin, and Firefox promptly removes it. It's nice to know (and quite surprising) that Firefox detects these changes - but how do I turn that off?

(I'm changing some .js code in an existing plugin to alter how it works.)