Obviously cannot from ctypes import NotepadPlusPlus.DockingDlgInterface, but wondering if you can create the tTbData structure:

https://github.com/npp-plugins/plugintemplate/blob/fd051e4cadaa2adcbedfdc27a817bc72eb0ae174/src/DockingFeature/Docking.h#L49-L63

and then register it:

SendMessage(notepad.hwnd, NPPM_DMMREGASDCKDLG, 0, (LPARAM)&data);

If you could pull it off? That would be a huge win allowing PythonScript to essentially be a full-fledged Notepad++ plugin creator scripting language.

Cheers.