Customize dock widgets behavior in QMainWindow

Hi all, I want to modify the behavior of QMainWindow so that the dock widgets inside always show with tab bar even it is single dock. Furthermore, the dock will float when user drag the tab out of the tab bar. Dig into the QMainWindow source code, such behaviors can be achieved by modify the internal QMainWindowLayout class. Anyone can share the experience about customizing QMainWindow? Modifying Qt source code and compile the whole Qt library is the only solution?