Glass UI Is Making a Comeback on Linux Thanks to KDE Contributors

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KDE Plasma’s two classic themes, Oxygen and Air, are making a comeback. A group of KDE contributors is actively restoring both ahead of the Plasma 6.7 release, which is scheduled for June 16, 2026.

Both themes trace their roots back to the KDE 4 era. Oxygen shipped as the default theme from KDE 4.0, defined by its dark tones and glassy aesthetic. It held that spot until KDE 4.3, when Air took over as the default, bringing a lighter look built around transparency and white as its base color.

While Oxygen stuck around into the Plasma 5 and 6 eras, it did so in an increasingly broken condition, and Air eventually got dropped from Plasma entirely.

Now, both are getting a second shot thanks to the restoration effort led by KDE contributor Filip Fila, alongside the original Oxygen designer Nuno Pinheiro and several other KDE developers.

On the Oxygen side, the panel has been fully reworked and is now orientation-aware, so vertical panels actually behave correctly. A minimized window indicator and a proper switch design were both missing entirely and have now been added.

Similarly, adaptive opacity is now supported and enabled by default, and the color scheme bug that was causing readability issues in widgets like System Monitor has been fixed.

Air needed its transparency restored to match its original KDE 4 character. That is done now, with blur added behind widgets, improving readability and visual appeal in the process. The panel has also been reworked, a new header and footer design has been added, and Air now has its own switch SVGs.

Why now after all this time? Well, KDE’s 30th anniversary coincides with the Plasma 6.7 release, and the people behind this want to ship these historically significant themes for the occasion.

As of writing, 26 of 40 checklist items have been completed (linked below), with some pending work including gradient banding fixes in Oxygen, missing SVGs for checkmarks, radio buttons, toolbar, and menubar items…

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