@Christian-Ehrlicher
Thank you, it helped!
In fact, these two commits contained what I needed:
Fix dragging a docked QDockWidget [REG-fix]
430985: Refix QDockwidget drag out dockwidget

@SGaist Thank you very much for the quick reply.

I've removed both the horizontal and vertical layout boxes and everything works exactly as I want.

Sometimes newbies make life more complicated for themselves than it needs to be!

Thanks again!

@eduardo_parra said:

but the cursor detect the margins

What margins?
Do you mean for something inside the docks?

@MrKozmon

I'm having the exact same problem on Android. When I drag a QQuickWidget that is hosting a QML-based WebView on Android, the widget moves but the WebView is left in the original position. Wondering if there has been any progress or a workaround for this issue.

I am using Qt 5.10.0, developing for an x86 Android platform.