So you want a modal dialog that is in fact loaded within a widget inside your QMainWindow class ? You can manually set the modality of your dialog with setModal.

@jsulm Okay, that helped me a lot. Thank you very much!

@VRonin Oh and you provide a model based solution. Much more elegant :) https://forum.qt.io/topic/72974/link-two-qlistwidget/4

@Radek Thank you very much Radek you helped me so much. even 4 years after your answer.

@kshegunov Thanks for your reply. Yes retrieving the child model via child and then setting data worked for me .

Hi, Isn't that pretty much the same question as here ?

@Chris-Kawa That's a valid point I hadn't considered. I'll just have to give this some more thought. It seems like maybe the most "Qt-correct" design would be to override childEvent(QChildEvent* event) to take the pointer into the member object when a child is added to the parent object. This would then, at least, bypass the need to call "findChild" over and over again.

Compiled and rebuilt with Qt5.5.0 (beta). Unfortunately, the problem persists.