Firefox 52 in 4MLinux 21.1
This is a minor maintenance release in the 4MLinux STABLE channel. The release ships with the Linux kernel 4.4.56. Additionally, some popular programs (Audacity, Chromium, Firefox, SMTube) have been updated, too. 4MLinux 21.1 includes the updated apulse package (backported from 4MLinux 22.0) to fix the problem with sound in the Firefox 52 series.
You can update your 4MLinux by executing the "zk update" command in your terminal (fully automatic process).