@Joe-von-Habsburg said in Add ready widget into widget: I am leaving an example QtCreator Preferences is your example?! So you want something similar?! You could dig into QtCreator source code and check out how it's done. For this I would use QToolButton to populate the "menu bar" on the left and a QStackedWidget to display the content pages on the right. Actually the QStackedWidget is more like centered, as the whole window you see is divided into two sections (~15% / ~85%) for the menu and the "rest" (the QStackedWidget for the content). Is it Qt designer form class (.cpp && .h && .ui)? The "right side" is the content widget... In case of QtCreator a custom QWidget containing a QTabWidget for the Text Editor settings among many other things. The parent of all this is probably a QStackedWidget as I presumed above. What approach (with or without Designer Form) you pick to implement this has nothing to do with how it works. Both ways are possible.

@silvio Show the code please. Any chance that the ui file is not used at all or the project overwrites the ui file layout by setting a new one using the widget's code?!

[image: 68c6ae62-ee82-4be1-ada6-7dd09767a7fa.png] am having the same issue . if I create a new project then select the Qt version 6 and then run the default code it produces no output .Ho do i fix fix this ? On the other hand if i start a new project and select the target Qt as Qt5 , it runs and produces an output.. so what could be the issue [image: 1f168880-152d-422b-bbc1-b9b9d6234b77.png]