@zipit @m_adam
Sorry, I forgot to mention that I'm developing in Python.
Thanks to your help, I seem to be able to display DescriptionCustomGui in my dialog only if I set an object to display via SetObject(), but this time I'm not seeking to display description of existing objects.
I'm still confused how to load .res file in description folder and display gadgets in my dialog.
Or is that impossible with .pyp ?

Hi,

I found that some of dialogs contain desc datas unlike others, for example Soft Selection Manager and Weight Manager. Also, those dialog's .res files are located in description folder, not dialogs folder.

And I tried to make a command plugin that open a dialog including desc datas via .res file in description folder, but I'm not sure how it works.

Does anyone know the way to build a dialog with those resources (especially Spline GUI) ?
I hope I'm not asking stupid question.
Thank you!