My original idea was to use tabs in MainWindow.
I do not like to have too cluttered application - with everything visible.
I like to have "tab" for each functionality

"scan for bt devices " - which btscanner does
then I like to have info about devices paired - not really necessary
then the actual communication via bluettoth - as a main tab


QMdiArea and QMdiSubWindow would keep too much "stuff" visible, but it would be fun (?) to try.