So I came here while researching for the problems with qt5 theme. So in the archi wiki it says -

3.1 QGtk3Style
This is a platform theme built into qt5-base starting with version 5.7.0 [2] and qt6-base. It can be used to style Qt5 and Qt6 applications according to current GTK3 style. It can be enabled by setting the following environment variable: QT_QPA_PLATFORMTHEME=gtk3. 

I am on nixos and if i set the same envionment variable qt6 apps like pcmanfm-qt, qbittorrent correctly use the same colors as my gtk3 theme, but it seems qt5 apps (like wpa_supplicant_gui, keepassxc, picard) even though in logs they seem to load the plugin, dont theme accordingly and show the default white color. I just want to know is the plugin abandoned? Meaning its no use trying to wait for it to update and be fixed or should i just switch to qtstyleplugins for qt5 apps?

I Can confirm this if i run

QT_DEBUG_PLUGINS=1 QT_QPA_PLATFORMTHEME=gtk3 wpa_gui 2>&1 | grep -i gtk3

and logs show

QFactoryLoader::QFactoryLoader() looking at "/nix/store/64qmp7fap3740hxd2bsnpy10s9ndy5qx-qtbase-5.15.18-bin/lib/qt-5.15.18/plugins/platformthemes/libqgtk3.so"
Found metadata in lib /nix/store/.../libqgtk3.so, metadata=
            "gtk3"
    "className": "QGtk3ThemePlugin",
Got keys from plugin meta data ("gtk3")
loaded library "/nix/store/.../libqgtk3.so"

• Note: The old qt5-styleplugins do work just need to set the variabled to gtk3 instead of gtk2

Side by side comparison

• qbittorrent (qt6 app)

Its using qt6, i can confirm
nix why-depends nixpkgs#qbittorrent nixpkgs#qt6.qtbase
/nix/store/i8r2n73xzlxk7sfchjlkdxajs8jbqbv0-qbittorrent-5.2.1
└───/nix/store/wzvm2pvf98a71v0scgfhmi01lqcxahfr-qtbase-6.11.0

• picard (qt5 app)

Its using qt5, i can confirm
nix why-depends nixpkgs#picard nixpkgs#qt5.qtbase
/nix/store/wzqlnryvnjl95a93fiwwivlbz3ypixk7-picard-2.13.3
└───/nix/store/64qmp7fap3740hxd2bsnpy10s9ndy5qx-qtbase-5.15.18-bin

I can confirm the same behaviour for the other aforementioned apps.

Edit: Turns out it was just qt5 apps acting up, wpa-gui has been ported to qt6 and is upcoming in next updates. and I have tested it, it correctly ports the gtk theme to qt.

So I came here while researching for the problems with qt5 theme. So in the archi wiki it says -

3.1 QGtk3Style
This is a platform theme built into qt5-base starting with version 5.7.0 [2] and qt6-base. It can be used to style Qt5 and Qt6 applications according to current GTK3 style. It can be enabled by setting the following environment variable: QT_QPA_PLATFORMTHEME=gtk3. 

I am on nixos and if i set the same envionment variable qt6 apps like pcmanfm-qt, qbittorrent correctly use the same colors as my gtk3 theme, but it seems qt5 apps (like wpa_supplicant_gui, keepassxc, picard) even though in logs they seem to load the plugin, dont theme accordingly and show the default white color. I just want to know is the plugin abandoned? Meaning its no use trying to wait for it to update and be fixed or should i just switch to qtstyleplugins for qt5 apps?

I Can confirm this if i run

QT_DEBUG_PLUGINS=1 QT_QPA_PLATFORMTHEME=gtk3 wpa_gui 2>&1 | grep -i gtk3

and logs show

QFactoryLoader::QFactoryLoader() looking at "/nix/store/64qmp7fap3740hxd2bsnpy10s9ndy5qx-qtbase-5.15.18-bin/lib/qt-5.15.18/plugins/platformthemes/libqgtk3.so"
Found metadata in lib /nix/store/.../libqgtk3.so, metadata=
            "gtk3"
    "className": "QGtk3ThemePlugin",
Got keys from plugin meta data ("gtk3")
loaded library "/nix/store/.../libqgtk3.so"

• Note: The old qt5-styleplugins do work just need to set the variabled to gtk3 instead of gtk2

Side by side comparison

• qbittorrent (qt6 app)

Its using qt6, i can confirm
nix why-depends nixpkgs#qbittorrent nixpkgs#qt6.qtbase
/nix/store/i8r2n73xzlxk7sfchjlkdxajs8jbqbv0-qbittorrent-5.2.1
└───/nix/store/wzvm2pvf98a71v0scgfhmi01lqcxahfr-qtbase-6.11.0

• picard (qt5 app)

Its using qt5, i can confirm
nix why-depends nixpkgs#picard nixpkgs#qt5.qtbase
/nix/store/wzqlnryvnjl95a93fiwwivlbz3ypixk7-picard-2.13.3
└───/nix/store/64qmp7fap3740hxd2bsnpy10s9ndy5qx-qtbase-5.15.18-bin

I can confirm the same behaviour for the other aforementioned apps.

[Solved] cross-posted from: https://lemmy.world/post/41957406

Exact problem as this archwiki forum post

I have also tried everything and at last here I am asking for any help, otherwise I don't think I would be able to continue using Linux on this laptop. I've tried everything from changing the kernel package to enabling all firmwares to using every kernel parameter I can find everything, nothing says any error or something anywhere. Only error i can find is hci device capabilities -22

Edit: The patch i needed was to add the driver info in btusb.c file. In nixos this is how you do it

  boot = {
    kernelPatches = [
      {
        name = "add-realtek-8852ce-btusb";
        patch = ./btusb.patch;
      }
    ];
}

first what you should do is git clone the linux kernel version you are using check using uname -r for me it was 6.12.(whatever, doesn't matter)

git clone --depth=1 git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git v6.12

then find the btusb.c file in drivers/bluetooth/ and add the line

{ USB_DEVICE(0x13d3, 0x3612), .driver_info = BTUSB_REALTEK |
BTUSB_WIDEBAND_SPEECH },

after these lines

static const struct usb_device_id quirks_table[] = {
 						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x0cb8, 0xc558), .driver_info = BTUSB_REALTEK |
 						     BTUSB_WIDEBAND_SPEECH },

now we have made chages to this file right? it will be shows in git diff, so now you should be able to do git diff > btusb.patch this will create a .patch file, now copy this file to wherever folder you put the nixos configuration in, most likely /etc/nixos if not using custom config. Thats it!, now rebuild the configuration and DONE. props to @Maiq.

Author of patch: vedantsg123

I will try to get this patch upstream to not having to do this manually.

[SOLVED] Exact problem as this archwiki forum post

I have also tried everything and at last here I am asking for any help, otherwise I don't think I would be able to continue using Linux on this laptop. I've tried everything from changing the kernel package to enabling all firmwares to using every kernel parameter I can find everything, nothing says any error or something anywhere. Only error i can find is hci device capabilities -22

Edit: The patch i needed was to add the driver info in btusb.c file. In nixos this is how you do it

  boot = {
    kernelPatches = [
      {
        name = "add-realtek-8852ce-btusb";
        patch = ./btusb.patch;
      }
    ];
}

first what you should do is git clone the linux kernel version you are using check using uname -r for me it was 6.12.(whatever, doesn't matter)

git clone --depth=1 git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git v6.12

then find the btusb.c file in drivers/bluetooth/ and add the line

{ USB_DEVICE(0x13d3, 0x3612), .driver_info = BTUSB_REALTEK |
BTUSB_WIDEBAND_SPEECH },

after these lines

static const struct usb_device_id quirks_table[] = {
 						     BTUSB_WIDEBAND_SPEECH },
 	{ USB_DEVICE(0x0cb8, 0xc558), .driver_info = BTUSB_REALTEK |
 						     BTUSB_WIDEBAND_SPEECH },

now we have made chages to this file right? it will be shows in git diff, so now you should be able to do git diff > btusb.patch this will create a .patch file, now copy this file to wherever folder you put the nixos configuration in, most likely /etc/nixos if not using custom config. Thats it!, now rebuild the configuration and DONE. props to @Maiq.

Author of patch: vedantsg123

I will try to get this patch upstream to not having to do this manually.

Make firefox look like this?