System information (version)

• OpenCV => master https://github.com/opencv/opencv/tree/13c6eb42e9788172c10132a35badacdb23de034b
• Operating System / Platform => openSUSE Tumbleweed
• Compiler => gcc 11.2

Steps to reproduce

Build OpenCV with Qt backend.

cmake .. -DBUILD_LIST=highgui -DWITH_QT=ON -DWITH_GTK=OFF -DHIGHGUI_ENABLE_PLUGINS=OFF

Run minimal program:

#include <opencv2/highgui.hpp>

int main()
{
    cv::namedWindow("img");
}

Result in

terminate called after throwing an instance of 'cv::Exception'
  what():  OpenCV(4.5.4-pre) /home/huangqinjin/Projects/opencv/modules/highgui/src/window.cpp:1257: error: (-2:Unspecified error) The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Cocoa support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script in function 'cvNamedWindow'

Issue submission checklist

• I report the issue, it's not a question
• I checked the problem with documentation, FAQ, open issues,
  forum.opencv.org, Stack Overflow, etc and have not found solution
• I updated to latest OpenCV version and the issue is still there
• There is reproducer code and related data files: videos, images, onnx, etc