OpenCV destroyWindow() not working with multiple windows - c++

Question

I am using openCV library to open and display multiple images. I am doing this with multiple windows created in order to display each image. In order to achieve display of multiple windows at the same time, I am using waitKey() only after the last image.
cv::namedWindow("Window1");
cv::imshow("Window1", myImage1);
cv::namedWindow("Window2");
cv::imshow("Window2", myImage2);
cv::waitKey(1000);
As can be seen from the code, my goal is to give the user 1s of time to press any key, otherwise I want to destroy one of the windows (for the purpose of this question it can be either one). I want to achieve this by using openCV's function destroyWindow().
Below my entire code can be seen:
cv::namedWindow("Window1");
cv::imshow("Window1", myImage1);
cv::namedWindow("Window2");
cv::imshow("Window2", myImage2);
cv::waitKey(1000);
cv::destroyWindow("Window2");
The goal of this code snippet should be that only "Window1" remains displayed, if 1s goes by, with the user not pressing any key.
However, this does not happen. The end result is that none of the windows are destroyed.
I have tested the following code snippet, which results in both windows being closed:
cv::namedWindow("Window1");
cv::imshow("Window1", myImage1);
cv::namedWindow("Window2");
cv::imshow("Window2", myImage2);
cv::waitKey(1000);
cv::destroyWindow("Window1");
cv::destroyWindow("Window2");
The same results when I use destroyAllWindows() function (which makes sense).
My question now is, why can't I destroy only one of the windows?
Additional info:
Using Ubuntu 20.04.
OpenCV version is 4.2.
Working in C++
Changing the order of which window I want to destroy changes nothing.

Answer 1

Tried to replicate it, facing this issue in Python as well on Ubuntu. If you are still stuck, you can try a stopgap solution of reshowing only the one you wanted to show provided the user has pressed a key or not by storing the result of waitKey in some variable. If it is -1 then no key has been pressed.
I have provided a sample solution in Python which you shouldn't face any difficulties converting to C++.
import cv2
img1 = cv2.imread('img1.png')
img2 = cv2.imread('img2.png')
cv2.namedWindow('img1')
cv2.imshow('img1', img1)
cv2.namedWindow('img2')
cv2.imshow('img2', img2)
key = cv2.waitKey(5000)
if key == -1:
cv2.destroyAllWindows()
cv2.imshow('img1', img1)
cv2.waitKey(0)
else:
# do whatever destroy both or keep on showing both using cv2.waitKey(0)
cv2.destroyAllWindows()

Answer 2

I have reached a solution by adding startWindowThread() before adding each of the windows.
An important thing to note is also that I have built openCV using GTK option, so my solution is tested only on GTK not on others.
startWindowThread() is used only with GTK as noted here: https://github.com/opencv/opencv/issues/7562 - for others the function is empty.