Debian: after upgrading the system the program became unusable. How to approach the problem?

JanuszSB · 27 Jan 2024, 18:55

The program is orphaned but it is very useful for me. More information in the opened issue: https://github.com/jsbien/djview4shapes/issues/5. Please note the screenshot on the main page of the repository.
The program used to work on bullseye, reportedly works on Kubuntu, it also works when crosscompiled for Windows.
This is for me a complete mystery, I have no idea how to approach the problem.

I will appreciate very much your suggestions, but please take into account that my knowledge of QT is rudimentary (I don't program myself but can understand some simple code).

P.S. This is my first post here, I don't tag my post as I don't know which tags would be appropriate.

Pl45m4 · 27 Jan 2024, 19:05

@JanuszSB

Hi and welcome,

under GitHub issue it's stated that the left panel does not open on Debian.
What widget/class is this? Any log / error message? Or just nothing?
I dont have a Debian system at hand to test it right now, but maybe there is something standing out in the code file.

JanuszSB · 27 Jan 2024, 19:48

@Pl45m4 said in Debian: after upgrading the system the program became unusable. How to approach the problem?:

@JanuszSB

Hi and welcome,

under GitHub issue it's stated that the left panel does not open on Debian.
What widget/class is this?

Sorry, no idea. I don't (yet?) understand the code.

Any log / error message? Or just nothing?

No errors reported at runtime, nothing suspicious in the compilation log.

I dont have a Debian system at hand to test it right now, but maybe there is something standing out in the code file.

Thank you very much for your interest, but I'm afraid it is Debian specific.

SGaist · 27 Jan 2024, 19:59

@JanuszSB Hi,

What exactly was upgraded ? Debian itself ? Qt ?

JanuszSB · 27 Jan 2024, 20:21

@SGaist said in Debian: after upgrading the system the program became unusable. How to approach the problem?:

@JanuszSB Hi,

What exactly was upgraded ? Debian itself ? Qt ?

A routine upgrade of Debian. Looks like Qt was upgraded automatically. To compile the program I had to remove qt5-default from dependencies and use qt6-base-dev.

The problem occurs both for the binaries compiled with Qt5 and the new ones compiled with Qt6,

SGaist · 27 Jan 2024, 20:41

@JanuszSB are you still on bullseye or did you uprage to bookworm ?

JanuszSB · S SGaist 27 Jan 2024, 20:21

@SGaist said in Debian: after upgrading the system the program became unusable. How to approach the problem?:

@JanuszSB are you still on bullseye or did you uprage to bookworm ?

Bookworm. I have still a virtual machine with bullseye and the program works there.

JanuszSB · wrote on 28 Jan 2024, 05:22

An update: I forgot I had an almost identical problem in 2020: https://github.com/jsbien/djview4shapes/issues/1. It was solved by Alexander Trufanov. His commit
https://github.com/jsbien/djview4shapes/commit/6bf0683671c1599dc6af0e16bebee4bcc5d7387e shows which fragment of code may be relevant for the present problem.

JanuszSB · 28 Jan 2024, 07:24

Looks like I found the culprit:
qt.qpa.wayland: Wayland does not support QWindow::requestActivate()
It works correctly under X.

So the upgrade of Wayland broke the program. How to fix it?

JonB · wrote on 28 Jan 2024, 07:24

@JanuszSB
Unless you get a better reply. There are quite a few features which used to work under Xorg but do not under Wayland, at least with the default compositor. Other than changing to X11 you are then stuck with the new behaviour, which is by design under Wayland.

Pl45m4 · 28 Jan 2024, 09:21

@JanuszSB

Might be helpful to read:

https://github.com/githubuser0xFFFF/Qt-Advanced-Docking-System/issues/288

SGaist · 28 Jan 2024, 09:40

@JanuszSB if memory serves well, you can use X application under Wayland. You can try forcing your application to use xcb backend.

JanuszSB · P Pl45m4 28 Jan 2024, 08:00

@Pl45m4 Very interesting link, but the solutions suggested there (XDG_SESSION_TYPE=x11, QT_QPA_PLATFORM=xcb) don't work for me.

JanuszSB · 28 Jan 2024, 14:53

@SGaist said in Debian: after upgrading the system the program became unusable. How to approach the problem?:

@JanuszSB if memory serves well, you can use X application under Wayland. You can try forcing your application to use xcb backend.

Yes, this should solve the problem. Unfortunately it is not clear how to do it. As I said above, QT_QPA_PLATFORM=xcb doesn't work for me.

For the time being switching to X at the login time is acceptable, but I will continue to look for a more elegant solution.

Pl45m4 · 28 Jan 2024, 17:33

@JanuszSB

On that linked page someone also mention that it might be fixed in Qt6.3+
At least the error message was gone, it I understand this right...
What version are you using? Can you upgrade?

JanuszSB · 28 Jan 2024, 19:59

@Pl45m4 said in Debian: after upgrading the system the program became unusable. How to approach the problem?:

@JanuszSB

On that linked page someone also mention that it might be fixed in Qt6.3+
At least the error message was gone, it I understand this right...
What version are you using? Can you upgrade?

qmake -query QT_VERSION reports 5.15.8 but I installed also qt6-base-dev .

The question "How do I install Qt 6 in Debian Bookworm?" (https://unix.stackexchange.com/questions/752145/how-do-i-install-qt-6-in-debian-bookworm) has practically no answer since 6 months :-(
QT is split on Bookworm into over 20 packages, installing all of them doesn't seem reasonable. I have no idea which of them I really need.
There is an option to install it from https://www.qt.io/download-qt-installer-oss, but I'm afraid of creating a mess by mixing various versions.

SGaist · 29 Jan 2024, 04:09

For the packages you need: look at the modules your application uses and just install those.

The Qt online installer does not mess with your system. It either install Qt in your home folder or in /opt so unless you do some pretty convoluted things, it will have no impact on your system.

JanuszSB · 29 Jan 2024, 05:40

@SGaist said in Debian: after upgrading the system the program became unusable. How to approach the problem?:

For the packages you need: look at the modules your application uses and just install those.

The Qt online installer does not mess with your system. It either install Qt in your home folder or in /opt so unless you do some pretty convoluted things, it will have no impact on your system.

Thanks for the information. Looks like I have some mess already :-(

I prefer to focus now on xcb. I have both
/usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/libqxcb.so and
/usr/lib/x86_64-linux-gnu/qt6/plugins/platforms/libqxcb.so.

qtchooser reports 7 (!) versions:
4
5
default
qt4-x86_64-linux-gnu
qt4
qt5-x86_64-linux-gnu
qt5

All of them has been installed some time ago just to compile two programs: djview4shapes discussed here and djview4poliqarp (https://github.com/jsbien/djview-poliqarp_fork); they share a lot of code, so it is a little strange that the latter has no problem with opening panels.

QTCreator reports 5.15.8 twice: /usr/lib/qt5/bin/qmake and /usr/lib/x86_64-linux-gnu/qt5/bin/qmake

So the question is: when I write QT_QPA_PLATFORM=xcb on the command line what actually happens? How to check whether the plugin is activated?

I noticed mentions of the platform parameter. Does it work for all programs? Should djview-shapes -platform xcb' work?

ChrisW67 · 29 Jan 2024, 06:26

@JanuszSB said in Debian: after upgrading the system the program became unusable. How to approach the problem?:

So the question is: when I write QT_QPA_PLATFORM=xcb on the command line what actually happens? How to check whether the plugin is activated?

QT_QPA_PLATFORM=xcb djview-shapes will start djview-shapes with QT_QPA_PLATFORM in the environment. When QApplication initialises it forces the xcb Qt Platform Abstraction (QPA) plugin where it would normally auto-select Wayland.

If you add QT_DEBUG_PLUGINS you see much more information about plugins found and loaded.
QT_DEBUG_PLUGINS=1 QT_QPA_PLATFORM=xcb djview-shapes

I noticed mentions of the platform parameter. Does it work for all programs?

Yes for anything using QGuiApplication or the QApplication subclass.

JanuszSB · 29 Jan 2024, 06:48

@ChrisW67 said in Debian: after upgrading the system the program became unusable. How to approach the problem?:

If you add QT_DEBUG_PLUGINS you see much more information about plugins found and loaded.
QT_DEBUG_PLUGINS=1 QT_QPA_PLATFORM=xcb djview-shapes

Nothing changed, no output. However if instead of xcb I write some other string then I get an error report.

In https://stackoverflow.com/questions/55731797/custom-plugin-for-qt-is-not-loaded-how-to-debug I found "you apparently have QT to build with debug information". Can it be relevant for my case?