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Volomike
Asked: 2019-05-02 21:44:53 +0800 CST

Lubuntu 19.04 Opens PCManFM-Qt Without Proper Theme As Root

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When opening PCManFM-Qt file manager as root from command line in Lubuntu 19.04, it opens using a default theme (which is rather ugly) and won't consider the choices made with lxqt-config. How do I change the root's lxqt theme so that PCManFM-Qt acknowledges it?

themes lubuntu pcmanfm 19.04 lxqt

1 Answers

  1. The answer is that it is considering your choice, but you don't have many applicable choices aside from Breeze/Windows/Fusion (none of which is a dark theme!). So you may want to install the package qt5-style-plugins, which enables the option "gtk2" in lxqt-config's Appearance section besides a few others. Selecting "gtk2" then makes the Qt theme engine imitate your GTK-2 theme.

    sudo apt install qt5-style-plugins

    Doing this prints the following:

    The following NEW packages will be installed:
  qt5-gtk2-platformtheme qt5-style-plugin-cleanlooks qt5-style-plugin-motif
  qt5-style-plugin-plastique qt5-style-plugins

    Now go to lxqt-config's Appearance, and select "gtk2" as the Qt theme. This applies your selected GTK-2 theme (e.g. Arc-Dark) as the Qt engine's theme. Log out and log in again to make sure it is completely applied (I noticed a few buggy incomplete details when not logging out, fixed after doing so).

    This other answer, specifically about the "gtk2" option, has a helpful screenshot.

    Explanation:

    As PCMan (the main developer of PCManFM-Qt) says in this GitHub issue, that file manager simply follows the default Qt theme engine, and there is no code to change that. This means that to change the styling of PCManFM-Qt, you must change the default theme of Qt applications.

    Lubuntu currently ships with only three themes, Breeze/Windows/Fusion, and as somewhat helpfully hinted in the dialogue, the way to try to make Qt apps follow a GTK theme is by selecting "gtk2" as the Qt theme.

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