Dolphin Theming Help QT

Help
1

After updating to nix 25.05 my theming mechanisms; I simply followed the example in this post. And now after updating its not working the way it used to.

environment.systemPackages = with pkgs;
  [
    libsForQt5.qtstyleplugin-kvantum
    libsForQt5.qt5ct
];
nixpkgs.config.qt5 = {
  enable = true;
  platformTheme = "qt5ct"; 
    style = {
      package = pkgs.utterly-nord-plasma;
      name = "Utterly Nord Plasma";
    };
};

I’m struggling on getting this working. I tried it for qt6, same issue. Nothing is taking. I don’t want to use stylix or home-manager (yet), I want something simple and works (as simple as the thing that used to work above). I just want everything in a dark theme, I don’t really care what at this point. Any ideas?

Also tried this:

  # night theme environment vars
  nixpkgs.config.qt6 = {
    enable = true;
    platformTheme = "qt6ct"; 
      style = {
        package = pkgs.utterly-nord-plasma;
        name = "Utterly Nord Plasma";
      };
  };
  environment.variables.QT_QPA_PLATFORMTHEME = "qt6ct";

Relevant packages enabled in my package list:

	lxappearance
	kdePackages.gwenview
  adwaita-qt
  adwaita-qt6
	materia-theme
	libsForQt5.ffmpegthumbs
	libsForQt5.kio-extras
	libsForQt5.kdegraphics-thumbnailers
	libsForQt5.qtstyleplugin-kvantum
  qt6Packages.qtstyleplugin-kvantum
	kdePackages.polkit-kde-agent-1
	kdePackages.dolphin
	kdePackages.qt6ct
	kdePackages.kde-cli-tools
	kdePackages.breeze-icons
	kdePackages.ark
	kdePackages.ark
	kdePackages.xdg-desktop-portal-kde
	kdePackages.kleopatra
  kdePackages.full

This is on an i3 setup fwiw

Referenced Post:

2

I’m pretty sure qt6ct doesn’t just automatically set the theme. Idk if home-manager manually configures by writing the theme name into its config. If not, run qt6ct in your terminal, then select the theme and close.

Also don’t set QT_QPA_PLATFORMTHEME manually, the home manager module does that for you.

3

Hello!

This setup configures Qt theming minimal declaratively, at the system level.
It works for Qt5 and Qt6, does not require Home Manager, and does not rely on GUI tools.

{ pkgs, ... }:
{
  environment = {
    systemPackages = with pkgs; [
      libsForQt5.qt5ct
      kdePackages.qt6ct
      adwaita-qt
    ];
    sessionVariables = {
      QT_QPA_PLATFORMTHEME = "qt5ct";
    };
    etc = {
      "xdg/qt5ct/qt5ct.conf".text = ''
        [Appearance]
        style=adwaita-dark
      '';
      "xdg/qt6ct/qt6ct.conf".text = ''
        [Appearance]
        style=adwaita-dark
      '';
    };
  };
}