Getting Qt application to honour dark theme on Lubuntu 26.04.1

miracletech322

What do you use?

miracletech322

Sent mail to [EDIT: Email address redacted -- JKSH]

Perdrix

We use Slack, but for this you could e.g. submit a PR or use a Github DIscussion. Note that I want the application to use the configured dark theme on Linux, not to apply a huge set of Style Sheets ...

miracletech322

Thank you for your reply.
miracle.tech322@gmail.com

Could you please invite me to your Slack workspace?
Also I think you should invite me to Git repo for creating PR.

Best regards.

Perdrix

You don't need to be a member of the GIthub authorised developers to submit a PR, just fork the repos, and once you have something working you can create a PR

miracletech322

I see.
After fix that feature, is it possible to hire me as your developer?

Perdrix

DeepSkyStacker is freeware and all development work is done by volunteers. No paid developers.

miracletech322

If so, I think you can invite me your Slack workspace..
I want to support DeepSkyStacker project with my skills and experience.
I will be waiting your Slack invite.
Thank you

JKSH

@miracletech322 Thank you for your willingness to help a community member. Please stick to the asker's preferred communication channels (Pull Requests or GitHub Discussions) -- this is the appropriate way to begin supporting their project.

Also, please do not post other people's email addresses publicly.

JKSH

@Perdrix said in Getting Qt application to honour dark theme on Lubuntu 26.04.1:

What do I need to do to get my Qt application to use a dark theme on Lubuntu?

The style I have set by default is "Fusion". On Windows the application changes according to which Windows theme I'm using but I can't see how to get this to work on Lubuntu.

The OS theme is normally exposed to Qt via the application palette. See:

https://doc.qt.io/qt-6/qguiapplication.html#palette
https://doc.qt.io/qt-6/qevent.html#Type-enum (ApplicationPaletteChanged event)
https://doc.qt.io/qt-6/qstylehints.html#colorScheme-prop
https://doc.qt.io/qt-6/qt.html#ColorScheme-enum

I would first check if you get the expected values when you query the above, or if you receive the ApplicationPaletteChanged event when you change the OS settings.

If not, that suggests that OS theme integration is missing from the QPA layer, so you'd want to raise feature request at https://qt-project.atlassian.net/. I suspect this might be the case as Lubuntu does not use GTK.

IgKh

Lubuntu is based on LXQt I believe, which is Qt based so it provides its own QPA Platform Theme (https://github.com/lxqt/lxqt-qtplugin). Also run your application with the QT_DEBUG_PLUGINS=1 environment to see if the lxqt plugin is found and used.

Perdrix

@JKSH I added code to report the colour scheme: 'Qt Info: (:0) Color scheme is: Light'

@lgKh The QT_DEBUG_PLUGINS output said:

root@charon:/home/amonra/Downloads# export QT_DEBUG_PLUGINS=1
root@charon:/home/amonra/Downloads# cd /opt/DeepSkyStacker/
root@charon:/opt/DeepSkyStacker# ./DeepSkyStacker
2026-10-30T09-10-04Z
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/plugins/platforms" ...
qt.core.plugin.factoryloader: looking at "libqxcb.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/platforms/libqxcb.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
    "MetaData": {
        "Keys": [
            "xcb"
        ]
    },
    "archlevel": 2,
    "className": "QXcbIntegrationPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("xcb")
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/platforms" ...
qt.core.library: "/opt/DeepSkyStacker/plugins/platforms/libqxcb.so" loaded library
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/plugins/platformthemes" ...
qt.core.plugin.factoryloader: looking at "libqgtk3.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/platformthemes/libqgtk3.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformThemeFactoryInterface.5.1",
    "MetaData": {
        "Keys": [
            "gtk3"
        ]
    },
    "archlevel": 2,
    "className": "QGtk3ThemePlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("gtk3")
qt.core.plugin.factoryloader: looking at "libqxdgdesktopportal.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/platformthemes/libqxdgdesktopportal.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformThemeFactoryInterface.5.1",
    "MetaData": {
        "Keys": [
            "xdgdesktopportal",
            "flatpak",
            "snap"
        ]
    },
    "archlevel": 2,
    "className": "QXdgDesktopPortalThemePlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("xdgdesktopportal", "flatpak", "snap")
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/platformthemes" ...
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/plugins/platforminputcontexts" ...
qt.core.plugin.factoryloader: looking at "libibusplatforminputcontextplugin.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/platforminputcontexts/libibusplatforminputcontextplugin.so, metadata=
{
    "IID": "org.qt-project.Qt.QPlatformInputContextFactoryInterface.5.1",
    "MetaData": {
        "Keys": [
            "ibus"
        ]
    },
    "archlevel": 2,
    "className": "QIbusPlatformInputContextPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("ibus")
qt.core.plugin.factoryloader: looking at "libqtvirtualkeyboardplugin.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/platforminputcontexts/libqtvirtualkeyboardplugin.so, metadata=
{
    "IID": "org.qt-project.Qt.QPlatformInputContextFactoryInterface.5.1",
    "MetaData": {
        "Keys": [
            "qtvirtualkeyboard"
        ]
    },
    "archlevel": 2,
    "className": "QVirtualKeyboardPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("qtvirtualkeyboard")
qt.core.plugin.factoryloader: looking at "libcomposeplatforminputcontextplugin.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so, metadata=
{
    "IID": "org.qt-project.Qt.QPlatformInputContextFactoryInterface.5.1",
    "MetaData": {
        "Keys": [
            "compose",
            "xim"
        ]
    },
    "archlevel": 2,
    "className": "QComposePlatformInputContextPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("compose", "xim")
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/platforminputcontexts" ...
qt.core.library: "/opt/DeepSkyStacker/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so" loaded library
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/plugins/styles" ...
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/styles" ...
Loading translator file [ "qt_en_GB" ] from path:  "/opt/DeepSkyStacker/translations"
Loading translator file [ "DeepSkyStacker_en_GB" ] from path:  ":/i18n/"
Loading translator file [ "DeepSkyStackerKernel_en_GB" ] from path:  ":/i18n/"
Operating System name: Ubuntu 26.04.1 LTS
Build architecture: x86_64-little_endian-lp64
Current architecture: x86_64
CPU Type: Intel(R) Pentium(R) CPU G4560 @ 3.50GHz
Physical Cores: 1
Logical Cores: 16
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/plugins/iconengines" ...
qt.core.plugin.factoryloader: looking at "libqsvgicon.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/iconengines/libqsvgicon.so, metadata=
{
    "IID": "org.qt-project.Qt.QIconEngineFactoryInterface",
    "MetaData": {
        "Keys": [
            "svg",
            "svgz",
            "svg.gz"
        ]
    },
    "archlevel": 2,
    "className": "QSvgIconPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("svg", "svgz", "svg.gz")
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/iconengines" ...
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/plugins/imageformats" ...
qt.core.plugin.factoryloader: looking at "libqgif.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqgif.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "gif"
        ],
        "MimeTypes": [
            "image/gif"
        ]
    },
    "archlevel": 2,
    "className": "QGifPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("gif")
qt.core.plugin.factoryloader: looking at "libqtiff.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqtiff.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "tiff",
            "tif"
        ],
        "MimeTypes": [
            "image/tiff",
            "image/tiff"
        ]
    },
    "archlevel": 2,
    "className": "QTiffPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("tiff", "tif")
qt.core.plugin.factoryloader: looking at "libqicns.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqicns.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "icns"
        ],
        "MimeTypes": [
            "image/x-icns"
        ]
    },
    "archlevel": 2,
    "className": "QICNSPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("icns")
qt.core.plugin.factoryloader: looking at "libqico.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqico.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "ico",
            "cur"
        ],
        "MimeTypes": [
            "image/vnd.microsoft.icon",
            "image/vnd.microsoft.icon"
        ]
    },
    "archlevel": 2,
    "className": "QICOPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("ico", "cur")
qt.core.plugin.factoryloader: looking at "libqtga.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqtga.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "tga"
        ],
        "MimeTypes": [
            "image/x-tga"
        ]
    },
    "archlevel": 2,
    "className": "QTgaPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("tga")
qt.core.plugin.factoryloader: looking at "libqsvg.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqsvg.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "svg",
            "svgz"
        ],
        "MimeTypes": [
            "image/svg+xml",
            "image/svg+xml-compressed"
        ]
    },
    "archlevel": 2,
    "className": "QSvgPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("svg", "svgz")
qt.core.plugin.factoryloader: looking at "libqwbmp.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqwbmp.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "wbmp"
        ],
        "MimeTypes": [
            "image/vnd.wap.wbmp"
        ]
    },
    "archlevel": 2,
    "className": "QWbmpPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("wbmp")
qt.core.plugin.factoryloader: looking at "libqjpeg.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqjpeg.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "jpg",
            "jpeg",
            "jfif"
        ],
        "MimeTypes": [
            "image/jpeg",
            "image/jpeg",
            "image/jpeg"
        ]
    },
    "archlevel": 2,
    "className": "QJpegPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("jpg", "jpeg", "jfif")
qt.core.plugin.factoryloader: looking at "libqwebp.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/imageformats/libqwebp.so, metadata=
{
    "IID": "org.qt-project.Qt.QImageIOHandlerFactoryInterface",
    "MetaData": {
        "Keys": [
            "webp"
        ],
        "MimeTypes": [
            "image/webp"
        ]
    },
    "archlevel": 2,
    "className": "QWebpPlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("webp")
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/imageformats" ...
Color scheme is:  Light
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqgif.so" loaded library
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqtiff.so" cannot load: Cannot load library /opt/DeepSkyStacker/plugins/imageformats/libqtiff.so: libtiff.so.5: cannot open shared object file: No such file or directory
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/opt/DeepSkyStacker/plugins/imageformats/libqtiff.so" : "Cannot load library /opt/DeepSkyStacker/plugins/imageformats/libqtiff.so: libtiff.so.5: cannot open shared object file: No such file or directory"
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqicns.so" loaded library
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqico.so" loaded library
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqtga.so" loaded library
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqsvg.so" loaded library
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqwbmp.so" loaded library
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqjpeg.so" loaded library
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqwebp.so" loaded library
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/plugins/accessible" ...
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/accessible" ...
qt.core.library: "/opt/DeepSkyStacker/plugins/iconengines/libqsvgicon.so" loaded library
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/plugins/accessiblebridge" ...
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/accessiblebridge" ...
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqgif.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqicns.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqico.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqtga.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqsvg.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqwbmp.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqjpeg.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/imageformats/libqwebp.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/iconengines/libqsvgicon.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/platforminputcontexts/libcomposeplatforminputcontextplugin.so" unloaded library 
qt.core.library: "/opt/DeepSkyStacker/plugins/platforms/libqxcb.so" unloaded library 
root@charon:/opt/DeepSkyStacker#

AFAICT it's not even looking for lxqt, so I suspect that @JKSH was correct in suspecting that there's no support for that in the QPA code. Guidance on how to phrase the request for lxqt support would be excellent.

Perdrix

PS how to unmark as Solved?

Perdrix

Hmmm some digging shows that the lxqt-qtplugin is shipped with the system as:
/usr/lib/x86_64-linux-gnu/qt6/plugins/platformthemes/libqtlxqt.so

But my install takes the theme plugins from /opt/DeepSkyStacker/plugins/platforms/platformthemes which contains plugins that were copied from /opt/Qt/6.10.0/gcc_64/plugins/platformthemes on my build system which doesn't include the lxqt plugin.

As lxqt does ship a suitable plugin, how can this be included as part of the Qt6 distribution for Linux (not the one that comes with the system as I have no control over the level of that!).

Looks like the QT distribution should also add a plugins/styles containing at least the Breeze and Kvantum plugins as shown here from the startup of an lxqt aware qt app (the desktop) on the system:

Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: qt.core.plugin.factoryloader: checking directory path "/usr/lib/x86_64-linux-gnu/qt6/plugins/styles" ...
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: qt.core.plugin.factoryloader: looking at "breeze6.so"
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: qt.core.plugin.loader: Found metadata in lib /usr/lib/x86_64-linux-gnu/qt6/plugins/styles/breeze6.so, metadata=
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: {
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "IID": "org.qt-project.Qt.QStyleFactoryInterface",
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "MetaData": {
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:         "Keys": [
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:             "Breeze"
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:         ]
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     },
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "archlevel": 1,
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "className": "StylePlugin",
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "debug": false,
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "version": 395776
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: }
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("breeze")
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: qt.core.plugin.factoryloader: looking at "libkvantum.so"
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: qt.core.plugin.loader: Found metadata in lib /usr/lib/x86_64-linux-gnu/qt6/plugins/styles/libkvantum.so, metadata=
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: {
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "IID": "org.qt-project.Qt.QStyleFactoryInterface",
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "MetaData": {
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:         "Keys": [
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:             "kvantum",
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:             "kvantum-dark"
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:         ]
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     },
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "archlevel": 1,
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "className": "KvantumPlugin",
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "debug": false,
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]:     "version": 395520
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: }
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: qt.core.plugin.factoryloader: Got keys from plugin meta data QList("kvantum", "kvantum-dark")
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: qt.core.plugin.factoryloader: checking directory path "/usr/libexec/styles" ...
Oct 30 09:10:05 charon org.freedesktop.impl.portal.desktop.lxqt[368070]: xdp-lxqt: Desktop portal registered successfully

Thanks, David

Perdrix

@Axel-Spoerl https://qt-project.atlassian.net/browse/QTBUG-151943

Perdrix

Hmmm. I tried copying the system version of the plugin to my plugins/platformthemes directory and Qt didn't try to load it.

I then tried export QT_QPA_PLATFORMTHEME=lxqt and got:

qt.core.plugin.factoryloader: looking at "libqtlxqt.so"
qt.core.plugin.loader: Found metadata in lib /opt/DeepSkyStacker/plugins/platformthemes/libqtlxqt.so, metadata=
{
    "IID": "org.qt-project.Qt.QPA.QPlatformThemeFactoryInterface.5.1",
    "MetaData": {
        "Keys": [
            "lxqt"
        ]
    },
    "archlevel": 1,
    "className": "LXQtPlatformThemePlugin",
    "debug": false,
    "version": 395776
}


qt.core.plugin.factoryloader: Got keys from plugin meta data QList("lxqt")
qt.core.plugin.factoryloader: checking directory path "/opt/DeepSkyStacker/platformthemes" ...
qt.core.library: "/opt/DeepSkyStacker/plugins/platformthemes/libqtlxqt.so" cannot load: Cannot load library /opt/DeepSkyStacker/plugins/platformthemes/libqtlxqt.so: /usr/lib/x86_64-linux-gnu/libQt6Svg.so.6: undefined symbol: _ZN14QObjectPrivateC2E16QtPrivate_6_10_2, version Qt_6_PRIVATE_API
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "/opt/DeepSkyStacker/plugins/platformthemes/libqtlxqt.so" : "Cannot load library /opt/DeepSkyStacker/plugins/platformthemes/libqtlxqt.so: /usr/lib/x86_64-linux-gnu/libQt6Svg.so.6: undefined symbol: _ZN14QObjectPrivateC2E16QtPrivate_6_10_2, version Qt_6_PRIVATE_API"

so this is definitely above my salary level :(

David

SGaist

Hi,

You need to build that plug-in with the Qt version you use to build your application. What happens is that you have Qt 6.10.0 loaded in memory for your application but that plug-in was built for 6.10.2.

Perdrix

@SGaist That makes sense, but OTOH I'd much prefer that Qt delivered it as part of the Qt distro ... and automatically searched for it. Hence the problem report I opened.

D.

SGaist

@Perdrix The thing is: that plugin is not part of Qt hence cannot be distributed with it.

Perdrix

So you are saying that the plugin for e.g. kde is part of Qt, and that you think it’s viable for me to tell my users to do their own build of the plugins, or that you think that I should build and ship them with my product??

The only way that makes sense to me is for Qt to ship them.

As things stand, the theme support just doesn’t work for any Lubuntu users.