KDE's Union theming engine can now style traditional QtWidgets applications like Dolphin and Kate, a breakthrough that required developer Akseli Lahtinen to write roughly 9,000 lines of QStyle code mapping CSS rules onto Qt's rigid painting framework. The second beta of Plasma 6.8 ships this expansion as part of Union's ongoing public tech preview, letting a single CSS file control the appearance of both modern QML interfaces and older C++ apps for the first time. The support is preliminary and KDE expects testers to encounter visual glitches, but the goal is clear: one styling pipeline for the entire KDE app ecosystem.
Plasma 6.8 is also the first KDE release to remove its X11 session entirely, going Wayland-only on the login screen while retaining XWayland for legacy app compatibility. For NVIDIA users, KWin will re-enable triple buffering by default after years of bug-fixing, which should deliver smoother frametimes on the desktop and in composited workloads. KWin now also requires plasma-wayland-protocols 1.23.0 to patch a memory leak.
On the tooling side, kup joins Plasma as a first-class backup scheduler module. It runs in the background, monitors when a backup destination becomes available, executes backup plans on a configurable schedule, and surfaces a system tray icon when an external drive is connected. Configuration lives in System Settings rather than requiring each distro to wire up its own solution.
Plasma 6.8 stable is targeted for 2026-10-14, a date that coincides with KDE's 30th anniversary. Testers who want to try Union now can install the union package, open System Settings, navigate to Colors and Themes, Application Style, and select "Breeze (Union)." Bugs specific to Union should be reported to KDE's Bugzilla, and the full changelog covers everything else landing in this cycle.
