6

Setup

When a Qt app (KeePassXC, AntiMicroX) is started automatically (via autostart), the GTK theme is not applied.

  • All apps are installed via standard apt packages (I am aware of snap theming issues).
  • I am on Ubuntu 20.04, I use the Yaru dark gtk theme.
  • To apply the GTK theme onto Qt apps, I did the following:
    • Installed the qt5-style-plugins apt package (with all of its dependencies)
    • Added a line to /etc/environment: QT_QPA_PLATFORMTHEME=gtk2
    • This works properly if I start the applications manually

Additional fiddling showed, that on cold start the theme never gets applied properly, however, on a restart, it does work sometimes.

Questions

  • How can I ensure that the dark gtk application theme gets properly used?

  • I would assume that when the autostart happens, some setting is not loaded, hence the breakage. Is there some sort of "service" those apps would have to wait for?

  • Should I try to add delay?

MrMeszaros
  • 767

2 Answers2

2

What made it work

Added a 1 second startup delay to the autostart desktop files (in ~/.config/autostart/):

[Desktop Entry]
...
X-GNOME-Autostart-Delay=1

This made the apps to start after the X session has properly initialized itself after login. Nothing else was needed (apart from the initial setup).

Notes

  • The QT Configuration tool (shipped in qt5ct apt package) is viable but not necessary.

    • If installed it addes an X session config /etc/X11/Xsession.d/99qt5ct that sets the QT_QPA_PLATFORMTHEME to qt5ct if unset.
    • It enables a wider configuration of Qt theming. I used a minimal ~/.config/qt5ct/qt5ct.conf:
    [Appearance]
icon_theme=Numix-Circle
standard_dialogs=gtk2
style=gtk2

  • For debugging the env of the apps can be checked with this shell command (note, I use fish and not bash): strings /proc/(pidof keepassxc)/environ | grep QT

  • To investigate where environment variables are set one can use these commands:

    # system wide - this was quick
grep QT_QPA_PLATFORMTHEME --recursive /etc/*
# per user - this was super slow on my system (*khm* steam *khm*)
grep QT_QPA_PLATFORMTHEME --recursive ~/*

  • Sources:

MrMeszaros
  • 767
1

On Xubuntu 20.04 LTS

First, install the Qt5 configuration tool with

$ sudo apt install qt5ct

Then, comment out the following line in /etc/X11/Xsession.d/56xubuntu-session by inserting a hash up front:

sudo nano /etc/X11/Xsession.d/56xubuntu-session
    # QT5 apps to use GTK style
    #export QT_QPA_PLATFORMTHEME=gtk2

Now, log out and in again. Changes made with Menu → Settings → Qt5 Settings will take immediate effect.

Serge Stroobandt
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