Am Mittwoch, dem 25.02.2026 um 15:05 +0100 schrieb Sven Hoexter: > On Wed, Feb 25, 2026 at 01:22:31PM +0100, David Ayers wrote: > > > I could get hold of an Ubuntu 25.10 desktop installation this morning, which > as far as I know uses a customized Gnome installation, and there vym picks up > the system dark theme. Window decoration is an instant change, application > menu > and canvas requires a restart. That was tested with vym 2.9.604 using the > default theme setting "System settings for dark theme". > Now the question is what might be the relevant magic Ubuntu applied. > From the perspective of the installed qt6 packages I see that > qt6-gtk-platformtheme is installed and qt6-qpa-plugins, but I'm not sure if > the later is relevant. I do not see any QPlatform reference > (https://doc.qt.io/qt-6/qpa.html) > in the vym code. >
The qt6-qpa-plugins also gets installed for the gnome desktop. Here
the full set up packages installed be the last command:
Start-Date: 2026-02-24 13:41:23
Commandline: packagekit role='install-packages'
Requested-By: ayers (1000)
Install: libb2-1:amd64 (0.98.1-1.1+b3, automatic), qt6-wayland:amd64
(6.9.2-3, automatic), libqt6wlshellintegration6:amd64 (6.9.2-3,
automatic), qt6-svg-plugins:amd64 (6.9.2-5, automatic), libxcb-
image0:amd64 (0.4.0-2+b3, automatic), libxcb-icccm4:amd64 (0.4.2-1+b1,
automatic), libts0t64:amd64 (1.22-1.1+b2, automatic),
libqt6quick6:amd64 (6.9.2+dfsg-5, automatic), xsltproc:amd64 (1.1.43-
0.3, automatic), libqt6network6:amd64 (6.9.2+dfsg-4, automatic),
vym:amd64 (2.9.604-1), zip:amd64 (3.0-15, automatic), qt6-gtk-
platformtheme:amd64 (6.9.2+dfsg-4, automatic), libqt6core6t64:amd64
(6.9.2+dfsg-4, automatic), libqt6qml6:amd64 (6.9.2+dfsg-5, automatic),
libqt6widgets6:amd64 (6.9.2+dfsg-4, automatic), libqt6dbus6:amd64
(6.9.2+dfsg-4, automatic), libdouble-conversion3:amd64 (3.4.0-1,
automatic), libqt6printsupport6:amd64 (6.9.2+dfsg-4, automatic),
libqt6gui6:amd64 (6.9.2+dfsg-4, automatic), gnome-themes-extra-
data:amd64 (3.28-5, automatic), libpcre2-16-0:amd64 (10.46-1+b1,
automatic), qt6-translations-l10n:amd64 (6.9.2-3, automatic), libxcb-
keysyms1:amd64 (0.4.1-1+b1, automatic), libqt6svgwidgets6:amd64 (6.9.2-
5, automatic), libxcb-cursor0:amd64 (0.1.6-1, automatic),
libqt6svg6:amd64 (6.9.2-5, automatic), libqt6waylandcompositor6:amd64
(6.9.2-3, automatic), libqt6qmlmeta6:amd64 (6.9.2+dfsg-5, automatic),
libqt6waylandclient6:amd64 (6.9.2-3, automatic), libqt6qmlmodels6:amd64
(6.9.2+dfsg-5, automatic), libxcb-render-util0:amd64 (0.3.10-1+b1,
automatic), libqt6opengl6:amd64 (6.9.2+dfsg-4, automatic), qt6-qpa-
plugins:amd64 (6.9.2+dfsg-4, automatic), libqt6qmlworkerscript6:amd64
(6.9.2+dfsg-5, automatic), libxcb-xinput0:amd64 (1.17.0-2+b2,
automatic)
End-Date: 2026-02-24 13:43:01
> > It may very well be an upstream logic bug here:
> > src/main.cpp
> > L424
> > // Use dark theme depending on system appearance and preferences
> >
> >
> > int text_hsv_value = app.palette().color(QPalette::WindowText).value();
> > int bg_hsv_value = app.palette().color(QPalette::Base).value();
> > systemSeemsDark = (text_hsv_value > bg_hsv_value);
> > QString settingsDarkTheme = settings.value("/system/darkTheme",
> > "system").toString();
> > usingDarkTheme = false;
> > iconTheme = "bright";
> > if (settingsDarkTheme != "never") {
> > if (settingsDarkTheme == "always" || (settingsDarkTheme == "system"
> > && systemSeemsDark)) {
> > usingDarkTheme = true;
> > iconTheme = "dark";
> > }
> > }
> >
> > I haven't wrapped my head around it yet but once I find time to figure
> > out how to actually build and install the package, I hope to be able to
> > provide a patch that could be submitted upstream.
>
> That should be fine, allowing you to override the system setting or
> if the system settings suggest it's dark, it's switching to the dark theme.
Ack...
> > PS: I did find:
> > https://www.debian.org/doc/manuals/maint-guide/build.en.html
> > which is actually target for maintainers but now I also found this:
> > https://wiki.debian.org/BuildingTutorial
> > so please give me the weekend, to see if I can figure this out...
>
> Rebuilding should be rather easy if you do it in place on a system with
> a deb-src configured to fetch source packages:
> apt source vym # grab the source package
> apt install build-essential fakeroot # get the general build tools in place
> apt build-dep vym # install the build dependencies
> cd vym-2.9.604
> dpkg-buildpackage -us -uc -rfakeroot # build the package
>
> Though I believe that shouldn't be necessary. At least the current Qt6 based
> version should be working fine.
>
Yes, I've got it do build (thank for the fakeroot bits... I actually
uninstalled vym and installed the built package successfully but I'll
use the fakeroot in the future).
But if the same code works for Ubuntu 25.10 and not for testing then I
guess I need to find a different rabbit hole... stay tuned.
Thank you, Sven!
David
--
David Ayers
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