Resize QWidget in QMainWindow

I have a main window derived from QMainWindow. I have a central widget and two docking widgets in this main window.
Now if i resize the main window, I want the dock widgets and the central widget resize proportionately , ie the widgets should appear same size in comparision to each other.

Is there some size property in main window to do this ?? or I have to capture resize event and manually change the size of my widgets ??

what is the best way to do this ??

have you used ?
myDockWidget->adjustSize();