SUMMARY While the theme includes some styling meant to be applied to the libhandy viewswitcher widget, it is currently not being applied, likely because the CSS selectors changed in libhandy version 1.0. STEPS TO REPRODUCE 1. Open an application that makes use of a libhandy viewswitcher with libhandy version 1.0 or above. OBSERVED RESULT https://invent.kde.org/plasma/breeze-gtk/uploads/1ab28e96f3a359a01514c1481d7803b3/demo-before.gif EXPECTED RESULT https://invent.kde.org/plasma/breeze-gtk/uploads/78eb208be70bd48e3117fe1acbe8f4fb/demo-after.gif SOFTWARE/OS VERSIONS Linux: 5.10.28-1-lts KDE Plasma Version: 5.21.4 KDE Frameworks Version: 5.80.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION This merge request uses an incorrect coding style, but demonstrates which CSS selectors can be used to successfully style the widget: https://invent.kde.org/plasma/breeze-gtk/-/merge_requests/18
This was fixed with the merging of that MR.