Thanks Andy. I get the message printed by 'printf("running .octaverc\n")' and now I don't need to press <Space> before closing any more. Furthermore, I wasn't able to close the GUI in any way other than executing "exit", now I can close it the same way as any Windows App. I guess it's a definite improvement. Below is my .octaverc file in case it can be improved even more:
##Some comments...
more off
printf("running .octaverc\n")
pkg load image #I've installed the image package during the installation of Octave itself.
more on
PS. I'd still like to know how to update the GUI.