KDE released the second beta of Plasma 6.8 today, carrying the pre-release number 6.7.91 ahead of the stable launch later this year. The headline update expands Union theming to legacy QtWidgets apps like Dolphin and Kate, finishing the second half of the engine's public preview. Kup, the btrfs-based backup scheduler, joins Plasma as a first-class module, making automatic backups to an external disk straightforward. The build also cuts X11 login support, defaults NVIDIA triple buffering, and packs in HDR, screen recording, and remote desktop improvements.

KDE Plasma 6.8 Beta 2 ships with Union theming for Qt apps and Kup backup

KDE's second pre-release build adds Union styling to legacy widget apps, folds in the Kup backup scheduler, and cuts X11 login support. The stable release is still months away.

KDE shipped the second beta of Plasma 6.8 on Thursday. The build carries the pre-release number 6.7.91, sitting just past the first beta at 6.7.90. Most of the ground between the two is bug work. Two additions, though, actually matter: Union theming now reaches legacy widget apps, and Kup, the backup scheduler, gets folded into the desktop proper.

What's in the box

Union is the headline. KDE's new theming engine aims to give every app a consistent, modern look that tracks the classic Breeze style. In Plasma 6.7, Union first showed up as a tech preview limited mostly to the newer QtQuick apps. This beta completes "the second half" of that preview, now also styling QtWidgets apps like Dolphin and Kate.

The catch is that KDE is upfront: it's buggy by design. To turn it on, you install the union package, open System Settings, go to Colors & Themes => Application Style, pick "Breeze (Union)", and hit Apply. Any leftover differences from Breeze count as intentional, not defects. KDE is asking testers to compare an app under Union against Breeze and report only genuine regressions. It's a structural bet on how KDE styles software, so the community testing matters more than usual.

Kup joins Plasma as a first-class module. It's a backup scheduler built on btrfs snapshots and compression. It existed before but flew under the radar. Now automatic backups to an external disk are a few clicks away, and btrfs copy-on-write semantics mean repeat backups consume little space. Not bad for something that used to mean "install a third-party utility and hope."

There are plenty of smaller touches too. HDR gets a boost with support for the HLG transfer function and better rendering when an ICC profile is in play. NVIDIA triple buffering is on by default now, which can smooth frametimes though it may nudge input lag up a touch. KWin's screen recording gains audio, remote desktop picks up bi-directional clipboard syncing, and Discover uses less memory when checking for updates.

Notable fixes and the odd details

Between the two betas, KWin picked up a memory-leak fix tied to the new plasma-wayland-protocols 1.23.0 dependency. It also fixes the lockscreen not appearing when you've chosen "never require a password", improves screencast timestamps, and corrects window-size logic in the Expo effect. Union got a big batch of work: tab rendering, menu-bar drawing, combo-box sizing, crash guards, plus restored icon handling and corrected mnemonics.

plasmashell, the core process, got fixes for the notorious isUiReady-never-going issue that could leave the desktop dead, plus panel sizing around the add-widgets button. Powerdevil's brightness applets had binding loops fixed. Kup can now report how long a job's been running.

And there's a fun aside: plasma-welcome added a special 30th-anniversary Konqi, the project's mascot. The 6.7.91 tarball for plasma-workspace alone comes in at 293 MB. The reach of these fixes is real — they span dozens of modules, from bluedevil to plasma-workspace-wallpapers.

One change that'll ruffle feathers: X11 login support is gone. New logins default to Wayland, with X11 kept only for strict legacy needs. It finalizes KDE's long pivot to Wayland. Keep in mind, though, that some older apps and hardware leaning on X11-specific features may need workarounds, so plan accordingly if you're running anything old-school.

Head here to the release page.