G4P Library / GUI builder: Move control from main window to panel or secondary window?

How do I move a control in G4P from the main window into a floating panel or a secondary window ? Ideally I would like to use drag and drop in the GUI builder tool, but it does not seem to support this. I tried fiddling with the code in the sketches GUI tab, but without success so I would appreciate help on how to achieve this without having to create each control new and with the changes showing up in GUI builder and not breaking GUI builder support for the sketch.

GUI Builder does not support drag-and-drop so if you place a control on the wrong window/panel then your only option is to delete it and create a new one.

The trick here is to think about the layout of your design before using GUI Builder