Marine1142:
What I did to get Stella to go full screen was when I start a game you hit "Tab" which brings up the video, audio, input selections...if you go to video, there is a box to check for fullscreen...just turn it on, should work. If you are using GameEx as your frontend, there is a command line for GameEx as well that starts Stella full screen that is preloaded...just make sure your working path for Stella is correct.
Chris, I'm anxious to hear something about your use of GameEx. I am also using GameEx, but when I send it to Stella in full screen mode, some of the image is off screen. Do you have a way - or know what we need to do - to do a full screen via GameEx that will show the entire playing field on screen?