Yep, that's pretty much the scoop, unfortunately. The manual and wiki both also mention this topic, with pretty much that conclusion. I don't think that having it stretch in windowed mode will be particularly straightforward or that it would look very good, as most of the time when that sort of stretching is in play, it looks pretty bad. But, I might be able to look at something with setting a multiplier on the orthographic camera, to see how that would look. Usually it leads to the graphics looking extraordinarily fuzzy, though, so I don't have high hopes -- hence why that is not a feature at the moment. See the stretch-to-window feature in AI War for example, it looks so horrible that I don't think anyone uses it. Wish I had better news!