PyObjC: how to create a simple dummy app without nib-file

For various reasons, I cannot/want not use a NIB-file (or any other external resources).

How can I create a simple du开发者_开发知识库mmy app (e.g. some simple menu, some empty window) with PyObjC, i.e. with pure Python code?

One very helpful introduction with sample code was the Introduction to PyObjC and Cocoa on lethain.com with some sample code here (and related files).

I also have an own project now (a music player) where I construct the whole Cocoa GUI dynamically. The main code of that part is here.