@AliQT
I'm afraid the Akismet post checker thing seems to ban a lot of legitimate stuff, especially with large code blocks. Really someone ought try to do something about this, you are not the first person to fall foul. I think I can see you have tried to enclose your code inside a pair of ``` lines, which is just the right thing to do but it still rejects it anyway.
It's hard to see from the two screenshots just what you have and what is wrong. A whole bunch of consequential errors in the first shot, probably depends on what the cause of the first error is. For the second shot, on the one hand I cannot spot what is wrong with the QTimer::singleShot() call but on the other hand it does not seem to have underlines an obvious error: in the first two methods visible on the left you have m_ui->... while in the third method you have m_ui.reset(). That cannot be right: either m_ui is a pointer (probably the case?) and is followed by -> or it is not a pointer and is followed by ., but not both. Perhaps the same for m_docs.
And if all a module sees is, say, class DocumentList, so a declaration that it is a class but no declaration of any of its methods, you will be able to write DocumentList *documentList and documentList = ..., because that does not need to know anything about its implementation, but you won't be able to call anything like, say, documentList->reset(), as it does not know anything about the members of DocumentList.
I will have a go now at copying that sample and dividing it into Application/DocumentList/Document module files for you. Will let you know when done and we will find some way of getting it to you.