I am trying to understand QDockWidget and see if I can get btscanner to be part of the MainWindow.
That might work. It depends on how you want your UI to operate. You could also check out QMdiArea and QMdiSubWindow as an alternative to docking widgets. If you add a QMdiArea as the central widget for QMainWindow, you can have multiple floating sub windows that can be tiled, overlapped, maximized, or minimized.