Should kvantum-dark be mentioned?

[francoism90]

I'm using Kvantum on GS to style Qt apps, which works really great. :)

However, when using QT_STYLE_OVERRIDE=kvantum on dark themes, it breaks text colors/make them unreadable.
It does work fine when using QT_STYLE_OVERRIDE=kvantum-dark instead.

Is this correct behavior? Should it be added to INSTALL.md?

Thanks!

[tsujan]

kvantum-dark was made for Gnome; otherwise, it's redundant and you could ignore it. It just switches to the theme "XDark" if the theme "X" has been chosen and "XDark" exists.

For example, if the active theme is KvGnome, kvantum-dark switches to KvGnomeDark.

Kvantum doesn't break text colors; bad hard-coded styles in apps may do it. Also, a theme that's made for Kvantum may have issues, but no theme that comes with Kvantum has such an issue.

[tsujan]

You're welcome.

I'll stick with kvantum-dark for now

If your active theme is called "Qogir-dark" and there's no installed theme with the name "Qogir-darkDark", kvantum and kvantum-dark will be exactly the same.

[francoism90]

When using QT_STYLE_OVERRIDE=kvantum-dark:

When using QT_STYLE_OVERRIDE=kvantum:

This also happens with inbuilt themes and QT_STYLE_OVERRIDE=kvantum:

It also doesn't work when using the default GTK-theme Adwaita. But everything does work fine when using QT_STYLE_OVERRIDE=kvantum-dark.

Is it something GTK/GS related?

[tsujan]

Do you have qt5ct installed and set?

I guess you work under a GTK DE like Gnome. GTK DEs usually don't have a Qt plugin (= "Qt platform integration program", as it's called in Kvantum Manager); so, you need to install one. qt5ct should work everywhere if it's set up correctly.

Anyway, in this special case, kvantum-dark tells Gnome that this is a dark theme but it won't be needed if there's a Qt plugin.

[francoism90]

Correct, I'm running Gnome(-shell) 41.

I'm using this one: https://wiki.archlinux.org/title/Uniform_look_for_Qt_and_GTK_applications#QGnomePlatform

I've tried using qt5ct, but this doesn't seem to apply any theme settings like colors correctly. That's why I'm using Kvantum instead.

[tsujan]

I've tried using qt5ct, but this doesn't seem to apply any theme settings like colors correctly

I'm afraid qt5ct is a platform plugin, not a style. It enables you to choose Kvantum or any other style (Kvantum has its own internal colors).

I think QGnomePlatform may have a problem or be too elementary or too limited. I remember that a Fedora user reported a similar issue but his problem was solved after installing and setting up qt5ct and also choosing Kvantum in it.

Unfortunately, Gnome is unfriendly toward Qt. In Qt DEs, like KDE or LXQt, the user doesn't need to know about "platform plugin", "style plugin" and their difference because everything needed is already installed.

I explain them briefly:

Since Qt5, a platform plugin is needed for choosing the Qt style and also the icon theme that's used by Qt apps. A platform plugin may also be called "Qt configuration plugin". Some platform plugins, like qt5ct, have a GUI that enables the user to select the icon theme and Qt style.

Qt style is sometimes called "Qt style plugin" or "Qt widget style". It's responsible for styling Qt apps. The default style of Qt is called Fusion but there are other styles like Kvantum, QtCurve, Breeze, etc. For changing the style, a platform plugin is needed, preferably with a nice GUI (like that of qt5ct).