KWallet, SecretService, oo7: the story so far

Continuing previous efforts to update the “secure passwords” story of the Plasma desktop, I’ve done some integration work between Plasma and oo7.

Oo7 is a relatively recent SecretService provider written in Rust; it’s very nice, lightweight and cross-desktop. Very interesting for us supporting it as a first class citizen.

We want in the end to replace completely the old KWallet system with something based on SecretService, have all our applications migrated transparently with user data as well, if possible with a cross-desktop backend implementation.

We also want it to be as transparent as possible for the end user, not having any complicated first time setup, or dialogs that ask for a manual unlock when not needed. For the user, the whole system should be just invisible, except when looking up their passwords or when client applications add passwords to it themselves.

As a first thing several months ago we did a transparent translation layer for the KWallet DBus interface, so now the “KWallet” service became just a translation layer between the kwallet api and the secretservice one.

The old kwalletd service instead became “ksecretd” now providing only the SecretService interface, and that’s what we use by default now. however, it can be configured to use a different provider, so it can already be used with gnome-keyring or KeepassXC if the user wishes. In that case the user data will be migrated the first time.

Also I’ve written a new application called KeepSecret. It is centered around SecretService, with a much more modern UI compared to KWalletManager and works also much better on mobile, so we can have also a modern password manager on Plasma Mobile.

KeepSecret running with the oo7 backend, with a native password dialog

The last thing that we did so far is integration with a new SecretService provider on the block: oo7.

If oo7 is Just another SecretSerive provider, Won’t it “just work” in Plasma? Not quite, but that’s actually a good thing. Oo7 wants to properly integrate with the environment it runs in, so we need to build that integration.

When you use KWallet, KeepassXC, or gnome-keyring directly, they create their own password dialogs using their own toolkits and styles, therefore potentially looking a bit alien when run in a different environment than the one it it was designed for.

This is not ideal for evaluating options for a possible future replacement of KWallet (which piece by piece we are working towards), as we want the UI part completely integrated with the Plasma desktop.

Instead, oo7 is built on the assumption that the environment it runs on will provide its own dialogs, a bit like the portal system for services like screen sharing and file picking.
This requires active integration both on the Plasma part and the oo7 part, but on the other hand it will look native on Plasma, Gnome, and any other platform that implements the integration hooks. And that’s with the added benefit of sharing the password storage if someone every now and then goes desktop environment hopping.

On the Plasma side we decided to employ a very small daemon which is launched only on demand with dbus activation. It will create the needed system dialogs, pass the user input back to oo7 and then quit when not needed anymore, so it won’t constantly use up system resources.

This is already available in Plasma 6.6: the code for it is here. It’s designed first for oo7, but it can be used by any daemon which wishes to provide native password dialogs, so we might start to use it also from other components in the future, either other SecretService providers or completely different things which have similar needs like Polkit.

On the oo7 part, Harald implemented the integration with its dbus interface, so with oo7 from main branch (or its next release) it can be used in place of KWallet (with all old applications still using the KWallet API using its backend as well), with all data migrated to it, and it will show native UI for its password dialogs… all the pieces of the puzzle slowly falling together 🙂

Needless to say this is still at an experimental stage, but it’s an important milestone in getting more independent from the aging KWallet infrastructure.

Pixel perfection

Sometimes an application can look kinda wrong due to very small details, few pixels can make or ruin the first impact. And since today a lot of monitors, especially laptop ones have to use fractional scaling, making things look sharp and pixel perfect is even harder.

Here is System Settings, on a screen scaled at 175%:

Here is zoomed, you can see some separators being one pixel, some other being two, usually blurred, making them appear of significantly different colors:

It was something that always annoyed me, so this is how System Settings will look with the next Kirigami that will come with the next Frameworks release in the beginning of November:

Here zoomed:

Separators are now 2 perfectly sharp pixels everywhere on 175%, giving the app a much cleaner look.

This will apply to every application which uses the Separator QML component. There are of course a lot of similar details fixes to do (and yes, I can see several ones still in the above screenshot), but sometimes small polishes can look like a big improvement 🙂

KWallet to SecretService, a client application: name wanted

As i wrote in the previous post, now the KWallet service has been splitted in a compatibility layer that exposes the old KWallet api, but actually consumes the Secret Service API, provided by default by the old KWallet daemon converted in a secretservice-only provider.

Another pain point is the application used to look inside the wallets, KWalletmanager, which only speaks the KWallet api and looks a bit dated nowdays:

I am working on a new application which goal is strictly to be a client for Secret Service. It can access passwords of any Secret Service provider (being KWallet, Gnome-keyring, KeepassXC, oo7 or whatever else) and should hopefully look a bit more modern and simple, while still being powerful:

Both as a desktop application or a mobile one:

For items imported from KWallet supports editing the values of type “Map” as well:

As well as visualizing “binary” entries (here super censored for obvious reasons 😉

The application can be tested at https://invent.kde.org/mart/kwallets

But has a fundamental problem, for which i need help… Right now is just called “KWallets” which can be kinda confusing with old KWallet and KWalletManager, so it probably needs a new name, any opinion is welcome 😄.

Towards a transition from KWallet to Secret Service

Historically passwords and credentials in all of our apps and services (such as kio and our Network Manager plasmoid), are stored and managed by our KWallet subsystem and API. In a similar way, GNOME had gnome-keyring, and other similar systems were available. A major problem was the mutually incompatible interface between them, making impossible to have a single place where all the passwords go.

For this reason, a standard DBus interface called Secret Service has been developed, and systems like KWallet, gnome-keyring and KeepassXC have adopted the interface as well.

In the future, we want to eventually port our applications to use the Secret Service API directly, preferably via the QtKeychain library (some applications already do), which will use Secret Service natively on Linux. And as a bonus the Windows/Android native systems on those platforms will work too.

This will make our applications work much better, be more integrated in other desktops or platforms, and be less dependent on the KWallet framework which has big legacy code parts at this point.

Right now, KWallet has the option to bring up a Secret Service compatible interface, and this is a valuable first step, but there are still some potential problems in the migration path:

Applications using Secret Service will store their secret data in different places when running in different environment, including our own that have been migrated. If you login into a different session ,every app will have forgotten its credentials.
It’s possible to use a different Secret Service provider also in a Plasma session, for instance enabling it in KeepassXC. At that point some apps will save into it, while other ones will keep using KWallet with a different storage backend.
Applications ported from KWallet to SecretService will lose their credentials, unless some clunky porting code is written for each application.

A KWallet compatibility layer

Enter the recent refactor that happened in KWallet: it has now been split into 2 different system services now: one that exposes only the Secret Service API, and one that exposes only the KWallet API.

The service exposing the KWallet API has been written from scratch and is now just a thin wrapper around the Secret Service API, translating the KWallet DBus calls to Secret Service ones. The old KWallet service is now a pure Secret Service provider that just happens to use the old KWallet backend, exposing to Secret Service all the entries that had already been stored in the past.

This decouples our KWallet compatibility layer for existing or old applications (not only KDE applications, also third party ones like Chromium use it) with our actual secret storage and SecretService implementation, allowing a separate development roadmap, and even potential future transition to a different backend in a completely transparent way to the user.

You can see this decoupling in the same spirit as the recent KWin Wayland/X11 split: being able to develop the new technology without risking breaking compatibility of the legacy system.

What it means for users and developers

For the immediate future, not much really changes: users will still have all their secrets accessible, and every app they use that was using KWallet will keep working without forgetting anything.

In the same way, for developers, the whole KWallet C++ API keeps working exactly as it was (even though we’re discouraging its use in new projects). Also, the KWallet-to-Secret-Service API proxy layer will save data inside Secret Service with the same schema used by QtKeychain, keeping the data accessible if the application gets ported from using the KWallet C++ API to QtKeychain.

An experimental feature

Disclaimer: The following description is of an experimental feature behind a hidden configuration key: it will take a bit before it’s deemed ready for prime time.

One advantage of having 2 independent services to handle the KWallet API and the Secret Service one is that now it’s possible to chose different backends as well, such as KeepassXC, gnome-keyring or oo7.

Setting the following in kwalletrc:

[Migration]
MigrateTo3rdParty=true
[KSecretD]
Enabled=false

With this, the old KWallet backend (now a service called ksecretd) won’t be started anymore, and instead any Secret Service provider that is running or has been configured to be DBus-activatable will be used. The first time this happens, a data migration procedure will be executed, writing the data in KWallet into the new service, keeping all the user-saved secrets accessible.

New Plasma Edit Mode in 6.1

In Plasma, when the user wants to do some significant layout change in the desktop, such as adding, moving or removing panels or add and manage desktop widgets, will go in the so called “edit mode”, by a context menu entry when driven by mouse, or by long-press in the desktop when driven by touchscreen.

Let me introduce you the improved edit mode workflow Plasma 6.1 will have:

An “edit mode” is necessary because since is an operation potentially destructive, we really want to avoid the user to for instance remove their own taskbar or some similar operation by mistake, during day to day use.

“Modes” in UI are a delicate thing: they have advantage as well many possible problems, which come in when it’s not immediately clear in which mode the user is in, and can try to use the UI as it was “in the other mode” (see https://www.nngroup.com/articles/modes/ as a quick introduction on advantages and disadvantages of modes).

This was a bit of a problem of the edit mode in plasma, as the edit mode was not clearly visually separated with the normal UI workflow of the day to day plasma usage.

Another problem present was that the action buttons of the edit mode toolbar were often hidden away by either the panel configuration window or the add widgets sidebar.

This new mode zooms out the desktop with the same visual effect of the window overview effect (yay for consistency), to well differentiate between normal and edit mode. Using the same zoom effect it puts the whole desktop “out of the way” when either the add widget sidebar of the panel configuration window appear, making sure the whole desktop area is always reachable, applets can be dropped anywhere in the desktop and the edit mode toolbar is always completely accessible.

Akademy 2023, Plasma 6 and Plasmoids

During this week Akademy 2023 is going on in Thessaloniki, Greece. It’s always awesome, to see many old friends and getting together with that amazing hacker community which is KDE.

There, me and Niccolò gave a talk about what;s happening in Plasma 6 and what will change, Noccolò on more visual things, about some changes we are cooking on the UI and on the visual themes. Here you can find a recording of the talk (alongside all the others of the day)

I talked more about the work I’ve bein doing in the Plasma shell during the last couple of months: code rafactors and how the API for writing plasmoids will change.

There were many things we were not quite happy about and now with the major release is the occasion for streamlining many things.

Now, It’s very important those changes are are well communicated, and easy to do for developes, because there are *a lot* of 3rd party plasmoids on the KDE store, which people are using and enjoying.

Let’s go trough the most important changes:

Dataengines

Dataengines were an API designed in early KDE 4 times, especially one of for our first offereings of Plasmoid API which was the pure JavaScript API, which existed long before the QML existed.

But now in a QML world, their API doesn’t really fit, instead is a much better fit having a QML extension which offers classes with all the needed properties, data models and signals that provide access to the needed data, such as tasks, notifications etc.

Dataengines are now deprecated and moved into a separed library, called “plasma5support” which will be still available for the time being, but consider porting away from it as we plan to eventually drop it.

Base Plasmoid API

The way plasmoids are declared in QML changed a bit: we used to have a magical “plasmoid” context property available from anywhere. This was an instance of a QQuickItem which was both the item where all the plasmoid contents were *and* a wrapper for some of the api for the central plasmoid object: the C++ class Plasma::Applet.

Now the access to plasmoid is an attahced property, the (uppercase) “Plasmoid”, which is directly the access to the instance of the central Plasma::Applet, without an in-between wrapper anymore.

The central QQuickItem is now called “PlasmoidItem”, and must be the root item of the plasmoid, just alike ApplicationWindow is for applications.

PlasmoidItem will have the purely graphical properties, such as the “compactRepresentation” or “fullRepresentation”

Here is a very minimal example of a plasmoid main file under plasma6:

import org.kde.plasma.plasmoid 2.0
PlasmoidItem {
    Plasmoid.title: i18n("hello")
    fullRepresentation: Item {....}
}

Actions

Plasmoids can export actions to their right mouse button menu, such as “mute” for the mixer plasmoid and so on.

In Plasma 5 we had an imperative API to add those actions, which was again coming from that old pure JS API, which really looked a bit out of tune in QML. In Plasma 6 the API has been replaced with a completely declarative API, in this form:

PlasmoidItem {
    Plasmoid.contextualActions: [
        PlasmaCore.Action {
            text: i18n("Foo")
            icon.name: "back"
            onTriggered: {...}
        },
        PlasmaCore.Action {
             ...
        }
    ]
}

PlasmaCore.Action is actually a binding to QAction (not the internal QML action type), so that it can be shared between C++ and QML easily

SVG theming

Plasma Themes don’t really have changed for now (and you can expect any old theme from the store to keep working), but the C++ and QML API for them has been moved to a standalone framework called KSvg. Plasma Svgs have quite some interesting features over the pure QtSvg API, such as disk caching of the rendered images, stylesheet recoloring to system colors and the 9 patch rectangular stretched images of FrameSvg.

Some applications were interested in using that, but couldn’t due to the long dependency chain of plasma-framework, so now they can be used as a much more manageable compact framework, offering both the usual C++, QPainter based api and QML bindings.

import org.kde.ksvg 1.0 as KSvg
FrameSvg {
    imagePath: "widgets/background"
}

Kirigami all the way down

Designing Kirigami in the beginning we lifted two concept from the Plasma API (which again we couldn’t use directly due to the dependency chain) Theme and Units

Theme gives access to the named system colors, and Units to standard spacing and animation durations.

Over the years the Kirigami version got way more advanced then the Plasma version, and having this code duplication didn’t make much more sense, to in Plasma6 whenever referring to a named color or an unit, the Kirigami version should be used, as the Plasma version is going away.

import org.kde.kirigami 2.20 as Kirigami
RowLayout {
    spacing: Kirigami.Units.smallSpacing
    Rectangle {
        color: Kirigami.Theme.backgroundColor
        bordere.color: Kirigami.Theme.textColor
    }
}

Plasma Sprint 2023

IT feels like a billion years before the last plasma sprint, which was in 2019 in Valencia, before the pandemic, but finally this year we are back on track, and was great to see again many old friends as well as seeing many new faces for which it was the first sprint.

We were gracefully hosted by Tuxedo Computers in Augsburgh, makers of very nice laptops that come with Linux and KDE Plasma, as well as being KDE patrons.

First of all, everybody got up to speed with a full git build of a Plasma 6 session, so that everybody could participate in development and discussions from the same level.

There were many discussions about Plasma 6, about what we want to do in Plasma and in Kirigami, how we want to change the look and defaults for the new major release. Most of the user-facing changes have been wonderfully described by Nate.

On my part, I worked on mainly 2 things, that were fairly not “glamorous” but quite important never the less (and mildly painful to do) : a refactor of the plasmoid loading code and splitting all the Svg themes code to a new framework with far less dependencies, ideally usable by any application.

Plasma API

I spent most of my hacking time at the sprint on a refactor of the plasmoid loading code, which won’t be really “seen” by the user, but will make the infrastructure much more robust and the API cleaner.

The person which must pay attention to it is the plasmoid author, which will need to adapt the plasmoid code in a few places.

Most notable is that, just like when you are writing a QML application you have to use the ApplicationWindow root QML Item, for a plasmoid you now have to use a PlasmoidItem root object, so something like

Item {
    Plasmoid.compactRepresentation: Label {text: Plasmoid.title}
    Plasmoid.fullRepresentation: Item {...}
}

becomes:

PlasmoidItem {
    compactRepresentation: Label {text: Plasmoid.title}
    fullRepresentation: Item {...}
}

A full porting guide is in progress.

KSvg

Using the Plasma Svg code to support stylesheet recoloring, on disk image cache to speed up loading, and the 9-patches FrameSvg is something the several applications would be interested to, and some actually are already doing, but since plasma-framework has a lot of dependencies, for some applications that is a blocker. All the svg code has now been broken out into a new framework called KSvg, which is still work in progress, but in the end will support all existing plasma themes with no change, and if an application wishes to use it, the svg sets will be loaded from the app own data folder (or anywhere else the application configures it to) instead of the share/plasma/desktoptheme folder, where plasmashell looks for them (so they can also use a complete different theme structure and don’t have to provide the same elements)

How to report Multiscreen bugs

As announced previously, Plasma 5.27 will have a significantly reworked multiscreen management, and we want to make sure this will be the best LTS Plasma release we had so far.

Of course, this doesn’t mean it will be perfect from day one, and your feedback is really important, as we want to fix any potential issue as fast as they get noticed.

As you know, for our issue tracking we use Bugzilla at this address. We have different products and components that are involved in the multiscreen management.

First, under New bug, chose the “plasma” category. Then there are 4 possible combinations of products and components, depending on the symptoms:

Possible problem	Product	Component
The output of the command `kscreen-doctor -o` looks wrong, such as: The listed “priority” is not the one you set in systemsettings Geometries look wrong	kscreen	common
Desktops or panels are on the wrong screen There are black screens but is possible to move the cursor inside them	plasmashell	Multi Screen Support
Ordinary application windows appear on the wrong screen or get moved in unexpected screens when screens are connected/disconnected Some screens are black and is not possible to move the mouse inside those, but they look enabled in the systemsettings displays module or in the output of the command `kscreen-doctor -o`	kwin	multi-screen
The systemsettings displays module shows settings that don’t match reality The systemsettings displays module shows settings that don’t match the output of the command `kscreen-doctor -o`	systemsettings	kcm_kscreen

In order to have a good complete information on the affected system, its configuration, and the configuration of our multiscreen management, if you can, the following information would be needed:

Whether the problem happens in a Wayland or X11 session (or both)
A good description of the scenario: how many screens, whether is a laptop or desktop, when the problem happens (startup, connecting/disconnectiong, going out of sleep and things like that)
The output the terminal command: kscreen-doctor -o
The output of the terminal command: kscreen-console
The main plasma configuration file: ~/.config/plasma-org.kde.plasma.desktop-appletsrc

Those items of information already help a lot figuring out what problem is and where it resides.

Afterwards we still may ask for more informations, like an archive of the main screen config files that are the directory content of ~/.local/share/kscreen/ but normally, we wouldn’t need that.

One more word on kscreen-doctor and kscreen-console

Those 2 commands are very useful to understand what Plasma and the rest of the system thinks about every screen that’s connected and how they intend to treat them.

kscreen-doctor

Here is a typical output of the command kscreen-doctor - o:

Output: 1 eDP-1 enabled connected priority 2 Panel Modes: 0:1200x1920@60! 1:1024x768@60 Geometry: 1920,0 960x600 Scale: 2 Rotation: 8 Overscan: 0 Vrr: incapable RgbRange: Automatic
Output: 2 DP-3 enabled connected priority 3 DisplayPort Modes: 0:1024x768@60! 1:800x600@60 2:800x600@56 3:848x480@60 4:640x480@60 5:1024x768@60 Geometry: 1920,600 1024x768 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: Automatic
Output: 3 DP-4 enabled connected priority 1 DisplayPort Modes: 0:1920x1080@60*! 1:1920x1080@60 2:1920x1080@60 3:1680x1050@60 4:1600x900@60 5:1280x1024@75 6:1280x1024@60 7:1440x900@60 8:1280x800@60 9:1152x864@75 10:1280x720@60 11:1280x720@60 12:1280x720@60 13:1024x768@75 14:1024x768@70 15:1024x768@60 16:832x624@75 17:800x600@75 18:800x600@72 19:800x600@60 20:800x600@56 21:720x480@60 22:720x480@60 23:720x480@60 24:720x480@60 25:640x480@75 26:640x480@73 27:640x480@67 28:640x480@60 29:640x480@60 30:720x400@70 31:1280x1024@60 32:1024x768@60 33:1280x800@60 34:1920x1080@60 35:1600x900@60 36:1368x768@60 37:1280x720@60 Geometry: 0,0 1920x1080 Scale: 1 Rotation: 1 Overscan: 0 Vrr: incapable RgbRange: Automatic

Here we can see we have 3 outputs, one internal and two via DisplayPort, DP-4 is the primary (priority 1) followed by eDP-1 (internal) and DP-3 (those correcpond to the new reordering UI in the systemsettings screen module).

Important data points, also the screen geometries (in italic in the snippet) which tell their relative positions.

kscreen-console

This gives a bit more verbose information, here is a sample (copied here the data of a single screen, as the output is very long):

Id: 3
Name: "DP-4"
Type: "DisplayPort"
Connected: true
Enabled: true
Priority: 1
Rotation: KScreen::Output::None
Pos: QPoint(0,0)
MMSize: QSize(520, 290)
FollowPreferredMode: false
Size: QSize(1920, 1080)
Scale: 1
Clones: None
Mode: "0"
Preferred Mode: "0"
Preferred modes: ("0")
Modes:
"0" "1920x1080@60" QSize(1920, 1080) 60
"1" "1920x1080@60" QSize(1920, 1080) 60
"10" "1280x720@60" QSize(1280, 720) 60
"11" "1280x720@60" QSize(1280, 720) 60
"12" "1280x720@60" QSize(1280, 720) 59.94
"13" "1024x768@75" QSize(1024, 768) 75.029
"14" "1024x768@70" QSize(1024, 768) 70.069
"15" "1024x768@60" QSize(1024, 768) 60.004
"16" "832x624@75" QSize(832, 624) 74.551
"17" "800x600@75" QSize(800, 600) 75
"18" "800x600@72" QSize(800, 600) 72.188
"19" "800x600@60" QSize(800, 600) 60.317
"2" "1920x1080@60" QSize(1920, 1080) 59.94
"20" "800x600@56" QSize(800, 600) 56.25
"21" "720x480@60" QSize(720, 480) 60
"22" "720x480@60" QSize(720, 480) 60
"23" "720x480@60" QSize(720, 480) 59.94
"24" "720x480@60" QSize(720, 480) 59.94
"25" "640x480@75" QSize(640, 480) 75
"26" "640x480@73" QSize(640, 480) 72.809
"27" "640x480@67" QSize(640, 480) 66.667
"28" "640x480@60" QSize(640, 480) 60
"29" "640x480@60" QSize(640, 480) 59.94
"3" "1680x1050@60" QSize(1680, 1050) 59.883
"30" "720x400@70" QSize(720, 400) 70.082
"31" "1280x1024@60" QSize(1280, 1024) 59.895
"32" "1024x768@60" QSize(1024, 768) 59.92
"33" "1280x800@60" QSize(1280, 800) 59.81
"34" "1920x1080@60" QSize(1920, 1080) 59.963
"35" "1600x900@60" QSize(1600, 900) 59.946
"36" "1368x768@60" QSize(1368, 768) 59.882
"37" "1280x720@60" QSize(1280, 720) 59.855
"4" "1600x900@60" QSize(1600, 900) 60
"5" "1280x1024@75" QSize(1280, 1024) 75.025
"6" "1280x1024@60" QSize(1280, 1024) 60.02
"7" "1440x900@60" QSize(1440, 900) 59.901
"8" "1280x800@60" QSize(1280, 800) 59.91
"9" "1152x864@75" QSize(1152, 864) 75
EDID Info:
Device ID: "xrandr-Samsung Electric Company-S24B300-H4MD302024"
Name: "S24B300"
Vendor: "Samsung Electric Company"
Serial: "H4MD302024"
EISA ID: ""
Hash: "eca6ca3c32c11a47a837d696a970b9d5"
Width: 52
Height: 29
Gamma: 2.2
Red: QQuaternion(scalar:1, vector:(0.640625, 0.335938, 0))
Green: QQuaternion(scalar:1, vector:(0.31543, 0.628906, 0))
Blue: QQuaternion(scalar:1, vector:(0.15918, 0.0585938, 0))
White: QQuaternion(scalar:1, vector:(0.3125, 0.329102, 0))

Important also the section EDID Info, to see if the screen has a good and unique EDID, as invalid Edids, especially in combination with DisplayPort is a known source or problems.

Multi Screen

Ah, working with more than one screen, nice and convenient, but always has been the scourge of usability, due to broken hardware and software, on every platform you can imagine. And yes, on Plasma we are notorious to have several problems with regard to multi screens, which spurred many bug reports.

TL;DR

For Plasma 5.27 we did a big refactor on how the screens are managed (and how they are mapped to desktops and panels) which hopefully should solve many of those issues, creating a much more predictable experience, both for “fixed” multi screen setups (like a setup at your desk) and “on the go” (like attaching a projector at a conference).

No more default empty desktops after connecting a screen that you already connected in the past
No more desktops, wallpapers, widgets and panels lost after restart
No more different sets of desktops between X11 and Wayland
Better experience when using USB-C based docks

UI wise on the Systemsettings module nothing will change in the most common case, when you have one or two screens, where you will be presented with the usual “primary” checkbox.

When you have 3 or more screens, instead of s simple “Primary” checkbox, you will be presented with a dialog where you can rearrange the screens in a logical order, so that you can say: “This is my screen number one, this is my screen number two etc.”

This will map exactly to what “screen number one, two etc” are for the Plasma shell, so that whatever desktops, wallpapers, widgets and panels are on the “screen number one” will always be on the “screen number one”, never disappearing again, same for each screen, giving a completely predictable, and stable multiscreen setup.

For 5.27 I worked mostly on the Plasmashell part, but many thanks and shouts to Ivan for his work on KScreen and to Xaver for his work on the KWin and Wayland protocol parts.

Long story: the moving parts

I would like to do a semi-technical but still quite high level description on how our multiscreen infrastructure works, and what did we change.

When you have multiple monitors connected, assuming the kernel and drivers will do the right thing (which… doesn’t always happen), either X11 or Wayland (so in our case the KWin Wayland compositor) will see the screens and have info about them we can enumerate and manage.

KScreen

In Plasma we have a daemon/library to manage the screens, called KScreen. It will save a configuration for each combination of screens it encountered. each screen is identified uniquely by its EDID, and when this fails for the above reasons, the connector name the screen is connected to (under X or libdrm they will have names like HDMI-A-1, DP-2, eDp1 and so forth). connector names are also not optimal, but is the best that can be done in case of a bad monitor (For 5.27 Xaver fixed a quite big issue on this fallback path which likely caused several of the reported bugs).

The user then can chose with the Systemsetting module how the screens are arranged, their resolutions, which is the primary and what not. When a screen is connected or disconnected, KScreen will search for an existing configuration for this set of screens and restore that one.

Plasma

The Plasma shell also has to be aware of multiple screens arrangement, because you want the desktops with their wallpapers, widgets and icons to be on the screen you expect it to, as well all the panels to be always on the “proper” screen you expect it to. And that’s where we had a lot of problems in the past, and various approaches have been attempted.

Current

Currently, up to 5.26 Plasma relied on two concepts for working out which screen a desktop and panel should be. Combining a single primary monitor and using screen connectors names for disambiguate second and third screens. In theory …

There are a couple of things that can go wrong with this: between X11 and Wayland, connector names tend to be different (for instance HDMI-1 vs HDMI-A-1 on my system).

Another problem is related to the the USB-C based docks that have video outputs (such as the Steamdeck one, but is common to any other model and brand). They dynamically create and delete the outputs and connectors when they are plugged and unplugged, but the connector name is not stable between different plugs/unplugs: sometimes after re-plugging the old names are not recycled, but increased (so for instance if those were DP-2 and DP-3, they may become all the sudden DP-4 and DP-5). Since we used to store those names, we have a problem: each time a new connector name is encountered is treated as a completely new thing, giving its new empty default desktop and no panels, causing many wtf moments.

Plasma Containments (technical name of the desktops and panels) always had a screen property associated to them which is just an integer: 0 for the primary screen and then 1,2,etc for the others.

5.27

The new approach builds on a single design, extending the primary monitor concept to multiple monitors, which cleans up the codepaths even for the two monitor case.

So we now dropped this association map between screen number integers and connector names, and we go with this ordered list all the way down, so now Plasma, KWin and KScreen agree exactly who “Screen 1” is.

We have a new Wayland protocol for screen ordering (as well an X11 counterpart) for KScreen and KWin to agree to which one is the real logical ordering of the screens, so Plasmashell will now follow this without attempting to identify monitors by itself, removing a very big failure point.

As said, When your system has only 2 screens, in the Systemsettings module you’ll see exactly the UI it had: just a checkbox to select which one is the “Primary”, so no surprises here. When you have 3 screens or more then you are presented with a dialog where you can visually reorder the screens, to decide which is the first, which is the second etc.

In this way, you’ll always be sure that whichever screen was set as “first” will have your “main” set of panels and desktop widgets, that you will never lose, also whichever you set as “second” will always have the desktop and panels you set it and never change and so on.

KWin and tiling

Personally I haven’t ever been a big user of tiling windowmanagers such as i3, awesome and what not, is not much the workflow style I want 24/7 out of my desktop, but there is definitely something something to say about that kind of multitasking when it makes sense, when is important to see the status of multiple windows at once for some particular task.

Plasma’s KWin has since a long time a basic support for tiles via the quick tiling support, by either dragging a window at edges or corners, or via keyboard shortcuts. This feature is very good, but very basic, and while there are 3rd party tiling extensions such as Bismuth which is a very nice thing, but window geometry managing outside the core always can bring you only so far.

Over the last month I have been working to expand a bit the basic tiling capabilities, both the quick tiling with the current behavior and a more advanced UI and mechanism which lets the user to have a custom tiling layout. Here it is a very short screencast about it.

tiling manager effect

Tiling is done by a full screen editor done as a fullscreen effect where is possible to add /remove/resize tiles. When moving a window if the Shift modifier is pressed, the window will be dropped in the nearest tile. Resizing the tile in the editor will resize all the windows connected, and on the converse, resizing tiled windows will resize the tiles as well. (also the traditional split screen quick tile will gain this feature, so if you have 2 windows tiled to get half of the screen each, resizing one will resize both)

Another use case we thought about for this tiling feature is to address people which have those fancy new ultra wide monitors.

Random stock photo from the interwebs of an ultra wide screen

There are very few applications which have an UI that actually make sense maximized on such proportions (i could imagine perhaps KDEnlive, Krita and very few other productivity apps). Most applications just look wrong, but with custom tiling areas, those can become sub “maximization” zones.

It is not intended to be a full fledged replacement for I3 or Bismuth, but rather an hopefully robust mechanism in the core with a pretty minimal and unobtrusive default ui, then the mechanism will have scripting bindings which should allow for 3rd party extensions to use it and implement interesting variations of the tiling WM out of it.

For now the feature is quite basic, a notable thing missing which i still hope to get in time for 5.27 is having separate tiling layouts per virtual desktop and activity (for now they’re per-phisical screen), but hopefully the full thing should land on a Plasma 5.27 release near you.

Mart

Tale of a little pixel