I am using QDockWidgets and placing two of them on the left side of my application so that tabs can be used to select between them. However, Qt\'s default behavior for this
If you are adding QTabWidgets to a main window derived from QMainWindow, you can try tabifyDockWidget.
It tabifies two QDockWidgets just like you wanted and of course you are able to drag them.
dockWidget1 = new QDockWidget("Tab1") ;
dockWidget2 = new QDockWidget("Tab2") ;
this->addDockWidget(Qt::LeftDockWidgetArea , dockWidget1 );
this->addDockWidget(Qt::LeftDockWidgetArea , dockWidget2 );
this->tabifyDockWidget(dockWidget1,dockWidget2);