If you have a main window which has several tab windows in a group, with dockOptions set to a combo of nested | tabbed | groupedDragging.

 

Set the features flag of each tab to Movable | Floatable.

In the constructor of your window, set the tab areas to North so tabs are on top:

Snippet

setTabPosition(Qt::AllDockWidgetAreas, QTabWidget::TabPosition::North);

 

Dragging the tabs from one dock area to another works fine.

 

However, floating one tab, then dragging another onto it exhibits a weird behavior: it flips the tab positions to South. Once you drag this floating group to a dock location, the tabs revert back to their usual location of North.

 

I believe I have found the code responsible for this:

 

https://github.com/openwebos/qt/blob/master/src/gui/widgets/qmainwindow.cpp

 

We see a lot of code like this which returns a default of South of the check fails:

 

return QTabWidget::South;

 

And if we look into that function, we see that it accounts for the 4 areas tabs can be docked at, but it does not account for what happens when a tab is floating and is not docked anywhere:

 

}

 

I think this might be easily fixable if we add an enum to account for the tabs being in a floating state.

 

Thank you.