For the Stopwatch Firefox Extension to work with K-Meleon 74.0 and K-Meleon 75.0 Beta, download Stopwatch
https://addons.cdn.mozilla.net/user-media/addons/1580/stopwatch-0.8.4-fx.xpi and rename it to
stopwatch@mercille.org.xpi
Next copy
stopwatch@mercille.org.xpi into the extensiosn folder.
Then download Stopwatch
http://kmext.sourceforge.net/extensions/stopwatch.7z from K-Mwleon Extensions Central
Last extract macros from Stopwatch
http://kmext.sourceforge.net/extensions/stopwatch.7z into the K-Meleon Root Folder.