Not PyGTK, but the Gtk from gi.repository :)
And don't put your subclass of Application in AboutDialog.py.
The Application should be the center of your app, so if i were you i'd put your class Application(Granite.Application) in pomidor/__init__.py, and instantiate it in main().
Look at how it is done in Vala apps, it is very similar to that.
Not PyGTK, but the Gtk from gi.repository :) Granite. Application) in pomidor/ __init_ _.py, and instantiate it in main().
And don't put your subclass of Application in AboutDialog.py.
The Application should be the center of your app, so if i were you i'd put your class Application(
Look at how it is done in Vala apps, it is very similar to that.