Hello there.
I am afraid that this problem might be very difficult to solve because I can barely give you any information, but maybe you have got an idea on how to solve it.
Quite a while ago, I successfully managed to integrate SFML into Qt (see
https://en.sfml-dev.org/forums/index.php?topic=19163.msg138596#msg138596 and
https://github.com/SFML/SFML/blob/master/src/SFML/Window/Unix/WindowImplX11.cpp).
I did it on Windows (MinGW), SFML 2.3.2, but it also worked on linux (g++).
Currently, I am working on linux. I compiled SFML 2.4 for myself with Clang. Now, when I start my Qt/SFML application, as soon as the GUI shows up, I get the error message
Failed to create input context for window -- TextEntered event won't be able to return unicode
exactly once, while I have two QWidget/sf::RenderWindow elements.
Edit: Actually, I found out that this happens once for every second QWidget/sf::RenderWindow element I add, which is very odd (or rather: even).
The application continues to run, however, the contents of those windows are not positioned correctly and the proportions are off. properly without any issues.I tried debugging but I cannot find out at which point the problem arises. I think it is somehow triggered by Qt when it starts displaying the application gui. Still, I do not think I changed anything of the window creation process since I worked with the older SFML version, so I wonder if something in the new SFML version changed the behavior.
Unfortunately, I cannot provide any minimal example code (as I cannot narrow down the problem's origin), but I can show you my Qt/sf::RenderWindow implementation class, which I attach to this post.
I also welcome general ideas on when the error message mentioned above can occur.