Hi,
The latest master have now the ability to control the size of the window. But not the position.
By the way, the good way to set the initial size is:
import kivy
kivy.require('1.1.2')
from kivy.config import Config
Config.set('graphics', 'width', '800')
Config.set('graphics', 'height', '600')
...
Before anything else in your application. We are working on a better approach to do this in the long term.
Mathieu