The KDE desktop gets an overhaul with Plasma 6

It's been nearly 10 years since KDE Plasma 5, which is the last major release of the desktop. On February 28 the project announced its "mega release" of KDE Plasma 6, KDE Frameworks 6, and KDE Gear 24.02 — all based on the Qt 6 development framework. This release focuses heavily on migrating to Wayland, and aspires to be a seamless upgrade for the user while improving performance, security, and support for newer hardware. For developers, a lot of work has gone into removing deprecated frameworks and decreasing dependencies to make it easier to write applications targeting KDE.

What's in Plasma 6

For the purpose of this article, we'll mostly look at Plasma and Frameworks, as Gear 24.02 contains too many applications like KMail, Kate, and the Kdenlive video editor that deserve more attention in their own right. I ran Fedora Kinoite's nightly releases with pre-release Plasma 6 packages, which has proved pleasantly stable and performant on an aging ThinkPad X280 with 16GB of RAM and a Core i7-8650U CPU.

The difference between Plasma 5 and 6 is apparent, but not pronounced. Users who are comfortable with Plasma 5 are unlikely to feel discomfited with Plasma 6, or have a hard time adapting to the changes sprinkled throughout the desktop. Plasma 6 has a number of changes to default settings. The big change, of course, is Wayland as the default graphical session.

Plasma 6 also has a smattering of smaller, less controversial changes. For example, prior to Plasma 6, the desktop defaulted to single-click to open a folder, launch a program, or open a file. Users coming from other operating systems or Linux desktop environments are often used to double-clicking to do these things. Now, KDE upstream has relented on using a single-click to open files and defaults to double-click instead. Distributions like Fedora, Kubuntu, and Manjaro had been changing the upstream default anyway, so KDE developer Nate Graham suggested disabling the feature. "Distros are closer to users and clearly the feedback they've been getting is that double-click is a better default...Let's admit it and switch to double-click by default ourselves".

Plasma 6 is also supposed to do away with the default of using the scroll wheel on the desktop to switch virtual desktops. However, this setting is still active in Fedora Kinoite as of this writing. Scrolling to switch virtual desktops has been the default for some time, but Graham argued in another proposal to disable the feature because it can easily surprise users with unexpected and unwanted behavior. Users who prefer the old behavior can toggle it back on in the "Mouse Actions" settings under "Desktop Folder Settings", so it's not going away entirely. Another change to scrolling behavior in this release is that clicking on a scrollbar moves the window to the location clicked, rather than one "page" at a time. This is meant to reduce the amount of fiddling with the scroll wheel to move up or down a long "distance", in order to be a better option for users with repetitive strain injuries (RSIs) — or for users who'd like to avoid RSIs in the first place.

Breeze is Plasma's default theme and it has been updated for Plasma 6, but it's a subtle change — sort of like repainting a room and changing the color from "flat white" to "eggshell white". It has some changes to spacing that make it feel a little less crowded, and it has fewer lines separating UI elements. The System Settings application has also been revamped. This may be more noticeable, as some of the settings have migrated to new locations. The nice thing about KDE is that so much is configurable, but finding configuration settings is still a challenge in Plasma 6. For example, the aforementioned setting to scroll virtual desktops is found in the Desktop Folder Settings application, but not in the System Settings application under the Virtual Desktop settings.

Dolphin, KDE's file manager, had its configuration settings redesigned to make them easier to navigate. The prior version of Dolphin included six tabs of settings for navigation, its context menu, startup behavior, view modes, behavior of the trash, and general settings. The redesign condenses this into four tabs, scooting the navigation options and startup options into the new interface tab. It also adds a fifth tab for user feedback, with options to contribute statistics and participate in surveys. These are, as one would expect from an open-source project that respects its users, set to share no data by default. Users who wish to participate, though, can choose just how much participation they're willing to engage in. This ranges from sharing just a few details like version of the application and operating system, to more telemetry like screen resolution, time Dolphin is used, how many network shares are available, and more.

The Dolphin interface changes are minor. Instead of showing recent files from today and yesterday, Dolphin now shows recent files and recent locations. Settings for file history are system-wide, and found in System Settings rather than Dolphin's settings — users can opt for keeping history "forever" or a period of months, or turn off history entirely. (Days or hours do not appear to be an option.) Users can also specify the applications allowed to access file history, rather than granting access to any application.

Plasma 6 on Wayland has some support for high dynamic range (HDR) and color management, depending on the application and if one has a supported monitor. Sadly, the monitors I have on hand are not supported. One thing that did work nicely, however, was setting the scaling for a laptop monitor and external monitor, independently. It was easy to set the external monitor to 100% scaling while the ThinkPad screen was set to 125% so that windows appeared to be the same size when moved from one monitor to the other.

The Plasma Search feature, which is part of KRunner and the Kickoff application launcher, has been refactored and is claimed to be much faster in this release. The release announcement claimed major speedups for searching local documents and for applications, while reducing CPU usage. It's hard to verify this, but KRunner did feel snappy when performing web and document searches. Spectacle, KDE's screenshot utility, now takes screenshots and recordings of the entire desktop, an application window, or just a selection of the screen. This promises to be a handy tool to create tutorials, or share a recording of application behavior when filing a bug.

KDE giveth, and KDE taketh away. As is common with major updates, some features and settings have been removed due to design changes or difficulty with underlying drivers or software. For example, GUI configuration for Synaptics touchpads and evdev input devices has been removed because the drivers have been superseded with libinput in Wayland. Unmaintained features like the Air theme, icon view for System Settings, and KHotkeys were all scuttled in this release. The ability to grab wallpapers from the Unsplash free stock image site was removed due to API changes and the QuickShare applet for file transfer was dropped because it never worked as intended.

Under the hood

Even though Plasma 6 may not feel like a major update, a lot of work has gone into KDE Frameworks 6 to make it possible. I asked KDE developer Carl Schwan by email about the developer-facing changes and plans for KDE 5 now that Plasma 6 has been released. Schwan said most of the work in Frameworks 6 was about reducing rather than adding features. Schwan pointed to removal of deprecated frameworks, like KHtml, the KJS javascript engine, and KHotkeys. The project has also worked to get rid of deprecated Qt APIs, such as QtCodecs, and to decrease dependencies between frameworks so external Qt applications can just use one or two KDE frameworks. Schwan also said that KDE has removed a lot of APIs "which were barely used or [...] have better alternatives either in another framework or in Qt itself". In particular, he noted that KDE's plugin system has moved from two APIs to a single API.

Schwan said that Qt 6 itself didn't have many API changes, but it did add an abstraction layer for graphics APIs like Metal, Vulkan, OpenGL, and DirectX "instead of only supporting OpenGL+Angle". In addition, Qt has switched to CMake, away from the qmake build system, which Schwan said helped a lot to improve developer tooling. Finally, Qt 6 brought a number of improvements to Qt Wayland, which Schwan said had been driven forward in part by KDE developers.

Support for KDE 5 and X11

Plasma 6 is likely to be a little bit rough around the edges for a while, and users might want to review known issues before deciding to upgrade. Obviously Plasma 6 won't be immediately available in most distributions, but users can refer to KDE's community wiki for instructions on how to test Plasma 6 right away. Users can choose to build from source, try the KDE neon testing edition, or try one of the other distribution-specific methods for Fedora, Gentoo, KaOS, NixOS, or openSUSE.

There is no rush to switch — KDE 5 is not quite out of the picture just yet. On February 12, on the Plasma development list, David Edmundson said he'd seen enough patches that should go into 5.27 to warrant another release. Justin Zobel agreed and noted that "many distros won't [adopt] it for some time. Major bugfixes and security fixes should definitely continue being applied until such time that most major distros have updated to 6". Valorie Zimmerman, from the Kubuntu project, said this is good news since the next long-term support (LTS) release for Kubuntu is coming in March and won't be based on Qt 6. On February 19, Jonathan Riddell reported the Plasma team planned to do a Plasma 5.27.11 release on March 6.

Even though many in the Fedora project are eager to drop X11 support, KDE upstream plans to continue including X11 support for users who depend on it in the short term. Users can expect to see support in Plasma 6 as well, but Schwan says there's "no fixed timeline" with various estimates ranging from two to five years before support is fully removed. He stressed that there will be "plenty of communication beforehand" and the project "certainly won't drop the support from one day to the other".

Overall, Plasma 6 looks to be a smooth upgrade for users, and KDE Frameworks 6 seems to be a solid foundation for the next few years of KDE development. It should be interesting to watch how Plasma evolves over the next few years.