Latest version of the MKVToolnix package for Slackware (Sbo build), build on a Slackware-current 15.0+ system. Requires Qt5.
For Slackware-current x64:
You might run into interface issues with this version: the GUI could show partially hidden interface elements, fonts, checkboxes, …
See the next link for more info (GitLab bug report): https://gitlab.com/mbunkus/mkvtoolnix/-/issues/3358
Solution is to create an ENV variable:
QT_AUTO_SCREEN_SCALE_FACTOR=0
Put it somewhere in /etc/bashrc or the user’s .bashrc. That should fix the interface issues.
Enjoy 🙂