I am confused by 'qt5ct'

Hello,

I'm confused by qt5ct in the LXQt edition.

By default when it's run it displays the message:

The application is not configured correctly.
The QT_QPA_PLATFORMTHEME environment variable is not set correctly (current value: lxqt, required value: qt5ct).

Why is it broken by default?

I can see that ~/.profile contains the line:
export QT_QPA_PLATFORMTHEME="qt5ct"
but this is clearly being ignored:

echo $QT_QPA_PLATFORMTHEME
lxqt

So presumably there's no point in this line being in ~/.profile.

If I add "QT_QPA_PLATFORMTHEME" "qt5ct" to the 'Environment Variables (Advanced)' section of 'LXQt Session Settings' and log out/in, then it does change:

echo $QT_QPA_PLATFORMTHEME
qt5ct

But then the theme becomes completely broken, and no amount of tinkering in 'Qt5 Configuration Tool' can fix it. For example, all the menu, desktop and file manager icons vanish, the file manager becomes unusable and the 'Show Desktop' panel widget turns into a big bar that says "Show Desktop"

In this post, it says that "You don’t need qt5ct on lxqt."

So what I'm wondering is: In light of all this, was it a mistake to include qt5ct in the LXQt version of Manjaro? Should I remove it? It's inactive by default (and this seems unintentional), and when it is active the desktop is unusable. If it wasn't a mistake to include it, why is it included?

Add to /etc/environment

What a strange reply.

Firstly, why would I want to do that? Did you not read all of my post?

Secondly, I tried what you said, in order to check whether it works... and it doesn't work.

What I meant is it will not work in bashrc or .profile, but if you set it in /etc/environment it will work.

Thank you for your reply.

I knew exactly what you meant. As an academic exercise, I tried adding the line to /etc/environment and then logging out/in, and it does not work. I tried four different forms of the string, and none of them work.

export QT_QPA_PLATFORMTHEME="qt5ct"
QT_QPA_PLATFORMTHEME="qt5ct"
export QT_QPA_PLATFORMTHEME=qt5ct
QT_QPA_PLATFORMTHEME=qt5ct

But as I said, I did this only as an academic exercise to test whether your advice worked. I do not want to set this environment variable. Indeed, I have already successfully set it using the GUI, and it broke the desktop. I am not asking how to set an environment variable.

I don't understand why you are trying to tell me how to set an environment variable.

Reboot maybe.
No reason to worry, is easy to login in tty and remove the export line in case of major problem. Why not try and find out yourself.

I'm posting this here because I've not had any luck in the Applications section. I wonder if people who are more familiar with LXQt will be able to answer:

I'm confused by qt5ct in the LXQt edition.

By default when it's run it displays the message:

The application is not configured correctly.
The QT_QPA_PLATFORMTHEME environment variable is not set correctly (current value: lxqt, required value: qt5ct).

Why is it broken by default?

I can see that ~/.profile contains the line:
export QT_QPA_PLATFORMTHEME="qt5ct"
but this is clearly being ignored:

echo $QT_QPA_PLATFORMTHEME
lxqt

So presumably there's no point in this line being in ~/.profile.

If I add QT_QPA_PLATFORMTHEME qt5ct to the 'Environment Variables (Advanced)' section of 'LXQt Session Settings' and log out/in, then it does change:

echo $QT_QPA_PLATFORMTHEME
qt5ct

But then the theme becomes completely broken, and no amount of tinkering in 'Qt5 Configuration Tool' can fix it. For example, all the menu, desktop and file manager icons vanish, the file manager becomes unusable and the 'Show Desktop' panel widget turns into a big bar that says "Show Desktop"

In this post, it says that "You don’t need qt5ct on lxqt."

So what I'm wondering is: In light of all this, was it a mistake to include qt5ct in the LXQt version of Manjaro? Should I remove it? It's inactive by default (and this seems unintentional), and when it is active the desktop is unusable. If it wasn't a mistake to include it, why is it included?

I cannot answer that. Maybe a Team member or the Manjaro LxQt maintainer can.

If your concern is theming, or just make it work (instead of correcting default LxQt setup), you may find these usefull
https://wiki.manjaro.org/index.php?title=LXQt
Launching
Miscellaneous
LxQt issues

I also use Manjaro LXQt. Although qt5ct is installed by default, I don't use it to customize LXQt. Instead, I do use kvantum + LXQt theme preferences, and it works. QT_QPA_PLATAFORMTHEME is set to lxqt.

People often skim through, so this is why it's good practice to try and summarize the problem and what you're trying to achieve in the first sentence/paragraph. Your title should also be more descriptive.

1 Like

Forum kindly sponsored by