commit ee9e1aac4ec225a7bc4360eee6c4da3c2432fd64
parent 1fb4081bfd350e32ccdece73565e001f0b6e4f27
Author: Luke Willis <lukejw@loquat.dev>
Date: Wed, 20 Aug 2025 15:35:53 -0400
Write post about theming QT
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diff --git a/posts/theming-qt-on-sway.md b/posts/theming-qt-on-sway.md
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+`((title . "Theming QT apps on Sway using Kvantum and lxqt-qtplugin") (date . "2025-08-20"));`
+This took me an uncomfortable amount of time to figure out.
+
+Long story short, QT doesn't really have a built-in mechanism to handle themes
+or icons. You have to use a style engine to change how applications look.
+[Kvantum](https://github.com/tsujan/Kvantum/tree/master/Kvantum) is great for
+this purpose and has a lot of nice built in themes. Once installed, you can
+simply set `QT_STYLE_OVERRIDE=kvantum` and QT apps will start using the theme.
+
+However, this still doesn't handle icons. Icons have to be handled through the
+`QT_QPA_PLATFORMTHEME` variable. Most DEs provide a weird plugin of their own
+that does some kind of black magic which can only be configured through a GUI.
+qt6ct/qt5ct are often advertised a fix for this, but they're both archived for
+some reason. Fortunately, [lxqt-qtplugin](https://github.com/lxqt/lxqt-qtplugin)
+works regardless of DE and has a simple configuration file format. This isn't
+really documented or advertised, but I did some digging into its code and I
+figured out how to use it. I'm personally using it alongside Sway, but it should
+work alongside any WM of your choice.
+
+It's two simple steps.
+
+1. Create `~/.config/Kvantum/kvantum.kvconfig` and modify it.
+
+This is self-explanatory.
+
+```
+[General]
+theme=KvSimplicityDark
+```
+
+Just put the name of your Kvantum theme there. If you want to select or preview
+the available themes with a fancy GUI, `kvantummanager` and `kvantumpreview`
+should be available (if you installed Kvantum, of course).
+
+2. Create `~/.config/lxqt/lxqt.conf` and modify it.
+
+This is mostly self-explanatory.
+
+```
+[General]
+icon_theme=Papirus-Dark
+
+[Qt]
+font="Sans Serif,12,-1,5,400,0,0,0,0,0,0,0,0,0,0,1"
+```
+
+If you're wondering about the weird font formatting, look up QFont. It's how QT
+reads font data. To make it simple, just copy this value, replacing "Sans Serif"
+with your desired font and "12" with your desired point size.
+
+2. Set `QT_QPA_PLATFORMTHEME=lxqt`.
+
+And you're done!
+
+Obviously, make sure lxqt-qtplugin and Kvantum are installed. Now everything
+will look nice and pretty. If you're curious how I manage this on GNU Guix,
+check out my personal set of Guix configurations,
+[orchard](https://git.loquat.dev/orchard/).
+
+Here's how [pavucontrol-qt](https://github.com/lxqt/pavucontrol-qt) looks on my
+system with this configuration.
+
+Before:
+
+
+After:
+
+
+Isn't that better?
+
+In Christ,
+
+Luke
