How to run the game in window mode?!

[w3sp]

Hey,

I want to run Penumbra in window mode but can't figure out how.
There is no such option in the graphic settings and alt+enter doesn't work either.

I've looked through the cfg files and found a Fullscreen="true" setting in default_settings.cfg which I changed to "false" and saved the file.
However the game still starts in fullscreen

Did I forget something? Do I have to execute the default_settings.cfg file on start or sth?

Please help me =)

thx in advance!
w3sp