No it wasn’t. The aspect ratio was always 4:3. The resolution changed from 640×350 (with non-square pixels) to 640×480 (with square pixels). But the aspect ratio did not change. (The first image in the article is therefore displayed incorrectly compared to what it would have looked like.)
But look at the clock icon at the bottom, that could definitely do with some vertical expansion to make it circular.
Yes? I never saw a "letterboxed" CRT. I think I'm with the people who are suspicious of the Windows 1.0 screenshot. Is there an emulator somewhere we can check with?
If you apply 4:3 aspect ratio, it becomes round.
https://www.reddit.com/r/imageuploads/comments/15zxpka/windo...
Note that "icon" here is the minimised state of the window, and the clock application draws itself in that state with the same code as in the normal state, and so it utilises screen metrics, while other minimised applications just call default windows procedure which puts bitmaps on the screen.