Thursday, 9 October 2025
It has been a little quiet around my pet project Plasma Browser Integration. On one hand because I’ve been busy with life but also because browser extension APIs haven’t really gained much new functionality. Nevertheless, for Plasma’s October release I finally found the time to take care of some long-standing feature requests and/or bug reports.

Plasma Browser Integration consists of two pieces: the “native” host and the browser extension. The extension is a regular JavaScript browser extension for Chromium-based browsers and Firefox and is distributed on the corresponding browser extension stores. The plasma-browser-integration-host on the other hand is a binary which talks to the system services (KRunner, KDE Connect, MPRIS, job tracker, etc) and is shipped as part of regular Plasma releases. Often a new feature requires changes to both parts which is why it’s hard to predict when a certain feature will actually be fully released. We also have to ensure that the extension remains compatible with potentially super old host binaries. Even the latest browser extension should work just fine with the host that came with a Plasma 5.27 LTS.
With Chrome sabotaging ad-blockers through Manifest Version 3 I am spending more time in Firefox again. The most notable new feature in Plasma 6.5 with the soon-to-be-released browser extension version 2.1 is that Plasma Browser Integration will prevent the system from going to sleep while downloading a file. Chrome does that on its own but the relevant Firefox bug report reached Ontario legal drinking age (reported against Windows XP), so I guess it was time to just do it ourselves. I recently added this functionality to KIO while copying files but there’s many more jobs that might want to do that. Therefore, I moved the logic into a dedicated KInhibitionJobTracker in KJobWidgets. You just register your job with this job tracker and the system will remain on for the entire duration of the task (on Windows, too!). When using KIO’s “dynamic job tracker” like most file-related operations, you get this automatically now.

Speaking of Firefox, Plasma’s volume applet now shows the name of the tab that is playing audio. This information is actually provided by Firefox itself (and I wish Chrome did the same) and not Plasma Browser Integration but we didn’t show that property until Plasma 6.4. Pretty neat to have it now. For accessibility purposes, Plasma 6.4 also added a playback speed selector to the Media Controller in your System Tray which works with most websites.
The KRunner plug-ins (tabs and history) now limit the favicon size they send. Some websites have 512px favicons which, while visually pleasing, is a little excessive for the places we show them in (KRunner or Kickoff). It further requests the list of open browser tabs from the extension only once at the beginning of a new “match session”. They’re unlikely to change in between because, well, you’re interacting with KRunner right now. While KRunner waited for the request to complete before sending another one, it might have still requested your tabs several times depending on how fast you typed.
Finally, something I had wanted for a long time is to download the album cover on the browser extension side. Previously, the extension collected the artwork URL from a website and announced it via MPRIS. The plasmashell would then load that image and display it. You can probably imagine why it’s not a good idea to have the shell load random files off the internet. It’s also why album art from the browser didn’t work on the lock screen because it rightfully has no network access. From Plasma 6.5, the browser will actually download the album cover. This way it’s done in the browser’s protected environment and can also refer to your session cookies. Further, it leaks less information about you if only your browser is accessing the server. While the resulting image file can still be potentially malicious, it’s one less attack vector. I tried to draw the artwork into an off-screen canvas to sanitize it to a PNG on the browser side but I wasn’t able to do that from the extension’s background script. If you have any more ideas how to make this feature more resilient, please let me know!







































































