SUMMARY
***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***
With this support it’s possible to enable some special font fetures such as small caps, discretionary digits, old-style digits, stylistic alternatives, and so on.

CSS have the ‘font-variants-liguatures’, ‘font-variant-caps’, ‘font-variant-numeric’, ‘font-variant-position’, and ‘font-feature-settings’ properties for them, and Pango and HarfBuzz also pave the way to handle special OpenType font features. So it’s possible to make the implementation.

STEPS TO REPRODUCE
1. Open an image
2. Click Text tool to insert a text
3. Add font-feature-settings in Text Editor

OBSERVED RESULT
No special font features enabled

EXPECTED RESULT
Krita’s Text Editor should be able to switch font features

SOFTWARE/OS VERSIONS
Windows: 10
macOS: 
Linux/KDE Plasma: 
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
Documentations at MDN Web Docs:
https://developer.mozilla.org/en-US/docs/Web/CSS/font-feature-settings
Samples from an individual developer:
http://tavmjong.free.fr/blog/?p=1442