linhusp/dolphin_and_kde_file_picker_on_niri.md

## dolphin_and_kde_file_picker_on_niri.md

      
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              dolphin_and_kde_file_picker_on_niri.md
            
          
    (Not Really) A Guide To Setup Dolphin & KDE File Picker On Niri - Arch Linux

My Thought On Making This

I have looked around online and noticed a lot of users that moved to Niri come from KDE, or were using Dolphin on their previous WM/DE and want to use it on Niri. The problem is that unlike Nautilus, the Dolphin experience on Niri is not out of the box, it has a lot of issues. 90% of the time you open Dolphin the first time it doesn't work properly and it looks horrible. So I try to write this to stealgather all the fixes that I have found and turn it into a guide for newcomers to make Dolphin functions as close as it was on KDE.
This guide focuses on Vanilla Niri. I personally don't use any plugin or theming shell so I don't know exactly how they work.
At the time I'm writing this I'm thinking of upload it into a gist or something at some point, to make it easier to update things and to access/download. Edit: gist

You should read the Niri wiki before this.

Goal

Is to simply make Dolphin, KDE file picker and KDE theming kinda work in Niri. The setup covers:

Thumbnails supports
Environment configuration
Dolphin losing default applications
KDE file picker as the default
Force KDE file picker on Firefox instead of the GTK one
Optional packages
Theming on Dolphin & KDE file picker

Bonus:

File pickers appears too big/fullscreen


1. Required Packages

These are the packages that SHOULD be installed:
+ dolphin
+ systemsettings
+ xdg-desktop-portal-kde
+ ffmpegthumbnailer
+ ffmpegthumbs
Note:


systemsettings
is the preferable way to change icons, themes and fonts on KDE that you can still use on Niri. It also let you customize other things that is not possible on alternatives like qt6ct.


xdg-desktop-portal-kde
comes with a bunch of depencencies but they are needed to replace the QT/GTK file picker with the KDE one.


ffmpegthumbnailer and ffmpegthumbs
provide thumbnails for images and videos on Dolphin/KDE file picker.


If you still want to use screen sharing/recording then DO NOT remove xdg-desktop-portal-gnome and xdg-desktop-portal-gtk. Unless you did something really wrong there is no problem using them along side xdg-desktop-portal-kde.


2. Environment Configuration (Critical)

2.1 Put the environment variables in ~/.config/environment.d/

~/.config/environment.d/
├── 01-xdg-base.conf
├── 10-kde-on-niri.conf
├── 80-gtk-no-btn.conf
└── 99-electron.conf
Only 01-xdg-base.conf and 10-kde-on-niri.conf are really needed. The others are optional. I just want to show an example how I structure the files for easier to overview or change certain variables you want.


01-xdg-base.conf
XDG_CONFIG_HOME=/home/<USER>/.config
XDG_DATA_HOME=/home/<USER>/.local/share
XDG_CACHE_HOME=/home/<USER>/.cache
XDG_STATE_HOME=/home/<USER>/.local/state

# REQUIRED: exposed native and Flatpak apps the same way KDE did
XDG_DATA_DIRS=/home/<USER>/.local/share/flatpak/exports/share:/var/lib/flatpak/exports/share:/usr/local/share:/usr/share


10-kde-on-niri.conf
QT_QPA_PLATFORM=wayland

# REQUIRED: make sure portal uses KDE Qt platform theme
QT_QPA_PLATFORMTHEME=kde
QT_QPA_PLATFORMTHEME_QT6=kde

# REQUIRED: helps fixing Dolphin default applications issue
XDG_MENU_PREFIX=plasma-

QT_AUTO_SCREEN_SCALE_FACTOR=1
QT_ENABLE_HIGHDPI_SCALING=1
QT_SCALE_FACTOR_ROUNDING_POLICY=RoundPreferFloor


80-gtk-no-btn.conf
GTK_DECORATION_LAYOUT=


99-electron.conf
ELECTRON_OZONE_PLATFORM_HINT=auto


Remember to run:
$ systemctl --user daemon-reexec
and then logout/login to apply.
2.2 Why not putting them in Niri's config file instead?

When you open for example Firefox or a flatpak application, it will activate the portal, in this case xdg-desktop-portal-kde. I believe it only inherits environment variables from systemd --user right after login.
Because niri-session starts after that, puting those variables in Niri config.kdl will not work as the portal cannot see it. So KDE apps spawned from these applications will still appear unthemed.

3. Dolphin Losing Default Applications

I think the direct cause comes from installing/removing packages and flatpak. If you:


Have exposed native & Flatpak paths and set XDG_MENU_PREFIX=plasma- like in the above.


Running once:
$ kbuildsycoca6 --noincremental


Auto start kded6
spawn-at-startup "kded6"


The problem will likely not happen again.

4. KDE File Picker As The Default

Edit ~/.config/xdg-desktop-portal/niri-portals.conf, make sure the default is gnome.
[preferred]
default=gnome;
org.freedesktop.impl.portal.FileChooser=kde;


5. Force KDE File Picker On Firefox

You need to make KDE file picker the default one first.
Then on Firefox, go to about:config and set
widget.use-xdg-desktop-portal.file-picker = 1

6. Optional Packages/Applications

These are not necessarily required or anything but they (could) provide a better experience for a Niri + Dolphin + KDE portal setup:


kde-gtk-config
to sync KDE settings to GTK apps. I'm not sure it will work 100% of the time, so you probably need the next one.


nwg-look
is a GUI option to change icons, themes and fonts on GTK apps.


breeze is a universal theme so it's a good way to check if everything works. These are the ones to install:

breeze
breeze-gtk
breeze-icons
(flatpak) org.gtk.Gtk3theme.Breeze


ark to open and manage archives, is integrated into Dolphin context menu.


filelight to view disk usage, is integrated into Dolphin context menu.


(AUR) qimgv is an order of magnitude faster than any distro targeted image viewer that is not borderline featureless. You can choose whatever version you want. Personally I recommend the qt6 version as I use qimgv-qt6-kde-git.


(AUR) gdk-pixbuf2-noglycin
as a workaround to GNOME upstream breaking changes on loading images involving glycin. You can read about it here and here.


(AUR) librsvg-noglycin
same reason as the above. Use this to replace librsvg if you have one on your system.


(AUR) libadwaita-without-adwaita

As the pkgname already said.
It also replaces libadwaita as dependency so you can freely remove libportal and nautilus if you want, while still keeping Portal GNOME intact.


7. Theming

Although the guide is primary for Dolphin & KDE file picker. You probably want other applications to look the same.
7.1 Dark variant

For example if you are using the default Breeze theme:


KDE apps
$ lookandfeeltool -a org.kde.breezedark.desktop


For GTK apps
$ gsettings set org.gnome.desktop.interface gtk-theme 'Breeze-Dark'
$ gsettings set org.gnome.desktop.interface color-scheme 'prefer-dark'


Or just use ksettings and nwg-look.
7.2 Hide decorations/buttons


For GTK, you can only hide the buttons on the title bar:
$ gsettings set org.gnome.desktop.wm.preferences button-layout "''"


For QT/KDE, if you set prefer-no-csd in niri it will hide title bar entirely.


7.3 Theming GTK2/3 and KDE/QT

There are quite of them that support both KDE/QT and GTK, like the Arc themes, Breeze, Matcha, Catppuccin etc. I don't have the best one to recommend.
7.4 Theming Flatpaks


The theme should be available on Flathub for Flatpak GTK apps to use it. If the theme are not there settings GTK_THEME in Flatpak's environment variables might work for a theme that support KDE/GTK3.


You may want to override these files to match custom fonts and settings on your system. Or easier use com.github.tchx84.Flatseal.
flatpak override --user --filesystem=xdg-config/gtk-3.0:ro
flatpak override --user --filesystem=xdg-config/gtk-4.0:ro
flatpak override --user --filesystem=~/.local/share/fonts:ro
flatpak override --user --filesystem=~/.config/kdeglobals:ro


7.5 Theming LibAdwaita apps

Now this's a tough one, here are the options I can think of:


Live with the default hardcoded by the developers and deal with it.


Stop using it and find the alternatives that your theme supports.

Personally I think this is the best option as I never like the gigantic title bars and elements. Plus the whole application looks completely out of place on everywhere else except Vanilla GNOME. In general I don't support this walled garden approach.


Replacing libadwaita with libadwaita-without-adwaita. As long as your theme supports GTK4, this will pickup the setting in org.gnome.desktop.interface.gtk-theme to load the GTK's palette into LibAdwaita. For example the Arc theme will work on LibAdwaita this way. There are still a few apps not looking correctly and this won't work on Flatpak LibAdwaita apps.


Use some programs to theme it like gradience or rewaita.

Not "truly theming", but at least you can tune the color palette to match your GTK/QT theme. I'm not sure about rewaita but I still keep some Breeze and Gruvbox gtk.css files generated from gradience. Even though the project already archived long ago it still works, probably will keep working until the next breaking changes of LibAdwaita.


There are some "theming engines" for QT+GTK+LibAdwaita out there. I could be wrong but most if not all of them are scripts that generated a material you palette from e.g pywal, then hacking the css file of Adw-GTK, while applying the same palette to Breeze. In a sense they are not much different than gradience.


There is a material you theming project but focus more on KDE kde-material-you-colors. I haven't had the time to look into this and test if it can work on Dolphin on Niri.


Bonus


8. File Pickers Appear Too Big/Fullscreen

This could be fixed by a window rule, something like this:
window-rule {
    # match title="^(Open|Choose|Save)(.*)$"
    match app-id="(xdg-desktop-portal)(.*)"
    match app-id="filepicker"
    match app-id="org.freedesktop.impl.portal.desktop.kde"
    default-column-width { proportion 0.5; }
    default-window-height { proportion 0.8; }
    open-floating true
    open-fullscreen false
}
8.1 Some applications still ingore window rule

There are some that are able to change the window's title immediately after spawning, so the window rules can't be applied. The biggest offender is Firefox.
It really depends on the application. For example with Firefox you can try this and see if it helps:
window-rule {
    match app-id="firefox" title="- (.*) Mozilla Firefox"
    default-column-width { proportion 0.5; }
    default-window-height { proportion 0.6; }
    open-fullscreen false
}
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