QDock Widget resizing

My Problem is – I have 2 QDockWidgets one vertical and one horizontal .
I have added custom title bar to the Horizontal dockWidget and Vertical dockWidget.
The Horizontal dockWidget has button for changing the visibility of that dockWidget .
The Vertical Dock-Widget has button which sets the visibility ON for the other dockWidget.

But when I hide the horizontal dockWidget the vertical dockWidget covers the area covered by the Horizontal Dock Widget.

The Best Example to Explain you my problem is – I want to provide the features to dockWidget as they work in Visual Studio. Can this be done ?

Which property of dock Widget I need to apply ? I have used the size properties of DockWidget.Or do I need to use the Properties of QMainWindow , is so Which property I have to use ??