The pamac GUI is GTK-based — gtk3 for pamac-gtk3 and gtk4 for pamac-gtk — so kvantum cannot have any effect on that.
It’s probably a matter of cache and/or permissions. Make sure that you clean out ~/.cache and that your dark themes are installed as they should be.
pamac is gtk-based and therefore uses gtk themes. On my system, those are installed in ~/.themes. There are however different configuration files for the different gtk generations under ~/.config.
KeePassXC is a qt5 application and will follow the qt theme as set in the Plasma System Settings, or in qt5ct if you’re not on Plasma.
If it’s not installed, then install it. It’s in the repository. And if it is installed, use it to select the theme for your qt applications.
Note: You have to set the qt style to kvantum in qt5ct in order to be able to load a kvantum theme into the kvantum manager.
Your package manager will tell you so, if only you look. keepassxc has qt5 as a dependency, and both of the pamac GUIs are gtk-based, as I already told you.
Unfortunately, after removing the now orphan kvantum-theme-matcha, what is left in the kvantum selector, like kvMatchaDarkSea or DarkAzul, is not dark at all. There are other dark themes working, but no matcha anymore.
So if you are using MatchaDarkSea for example in the Appearance settings and want a matching experience in Qt, dark, kvantum-theme-matcha is still the only way. Old or not, you may remove it from default dependencies, but pretty please do not remove it from the repos.
Inrerestingly, with both KeePassXC and Pamac up and by cycling through the inbuilt adwaita and matcha’s in “appearance” I can see the only dark theme that works is Adwaita-dark which is what I use and this is the status before today’s updates.
So looking like find a dark theme on internet or see what other distros do these days…
You are on XFCE … which is not only GTK , but a turtle in terms of development.
So its behind other GTK desktops like Gnome, which is now using GTK4 (And specifically libadwaita) … which is not going to be supported by every theme that ‘works’ on XFCE. pamac now is also gtk4 (and libadwaita)
If you want an older pamac, for now you can use pamac-gtk3
Removing kvantum is a very drastic “solution”, if one continues to use QT apps, they will be even more ugly.
And pamac is either a gtk3 or gtk4 app so it does not use kvantum anyway.
Just don’t remove the now orphaned matcha package, or select another similar dark theme from kvantum, like the adwaita ones work.
If a distro-supplied kvantum theme is removed from the repository, then the user can still use it by fetching the theme from store.kde.org, save and unpack the tarball in their $HOME somewhere, and then load the theme into the Kvantum Manager. kvantum will then store the theme in its configuration directory under $HOME/.config/Kvantum.
