KDE has released the second beta of Plasma 6.7, and the headline addition is a public tech preview of Union, a new theming system that will eventually replace the long-standing approach to styling Qt and QML applications across the desktop. Two new modules ship with this release, plasma-bigscreen and union, and the project is asking testers to put the new framework through its paces.
Union can now be enabled globally by selecting it as the Application Style under System Settings, Colors and Themes, Application Style. Applications need to be restarted after the switch. For more targeted testing, developers can launch a single QML-based app with the environment variable QT_QUICK_CONTROLS_STYLE=org.kde.union [program name], pointing at binaries like systemsettings, plasma-systemmonitor, plasma-discover, or spectacle. KDE warns against exporting that variable globally, since doing so will break Flatpak applications.
The goal for this first preview is visual parity rather than reinvention. Apps styled with Union should look as close as possible to their appearance under the current Breeze style, with any small improvements treated as intentional rather than a redesign. Comparing behavior is straightforward: run the same application with Breeze selected or without the environment variable set, and any Union-specific regressions can be filed against the Union bug tracker.
A broader rundown of the changes landing in this cycle is collected on the KDE community wiki. Feedback during the beta window is being gathered through the KDE Forums, the #Plasma Matrix channel, and the Plasma-devel mailing list, with Bugzilla as the formal path for issue reports.
