The idea of Qt operating in one sub-interface to modify the control content of another sub-interface

Named separately: sub-interface A, sub-interface B, control b of B to be modified

purpose:在子界面A中修改B的控件

1. Object of B declared in Ah
2. Instantiate the B object in A.cpp
3. Implement the public method funB() in B.cpp, pass the content to be modified as a parameter, and use B's own ui to modify the content of the control in the method.
4. By calling the funB() method of B in A.cpp