how to build app container in Python or Matlab

I have just started learning Python.

I would like to build an application with bar menus and different windows contained inside what I think coders call a ‘boiler plate’ a window containing everything.

The app has to contain also pull-down menus with file handling, settings, functions .. some are repeated inside windows contained in the boiler plate.

The app would like this

I started writing the app in Matlab but I could not build the ‘container’ windows, the boiler plate, pull-down menus all in one app.

Is there a Python package to start with and write something like the screen shot above?

Thanks for time and attention