Take a look at QCAD dock

[luzpaz]

http://www.qcad.org/en/

[nitramr]

They uses a QDockWidget too. It is the same implementation like in offical Scribus repository.

[luzpaz]

They use the horizontal dock as well. But I was wondering if they used any of your code as well ?

[nitramr]

I couln't found any of my code. However, the standard QDockWidget support horizontal docking too. I think the magic happens in the content widget management inside the dock. The QCAD project uses a floating layout, which comes from Qt itself.
http://doc.qt.io/qt-5/qtwidgets-layouts-flowlayout-example.html

In the origin project of my IndigoDock plugin I'm was experimenting with this layout type, but for a working usage we need to split the widgets of Scribus panels into small pieces/blocks which can float.

Maybe we can build an simple prototyp in form of a html page. We can put some blocks there and define a floating behavior which we can easily test in a browser with different resolutions. Such prototyp is easy to update and we can test the layout without compiling code.

I made a quick research about frameworks and I found one of jQuery, here a demo page:
http://demos.jquerymobile.com/1.4.5/theme-default/

This looks more like desktop applications:
http://www.zebkit.com/