In ZDoom, textures can now be up to 254 pixels tall and will properly repeat if they are 1, 2, 4, 8, 16, 32, 64, or 128 pixels tall. These are special cases that were easy to fix. Other heights will still exhibit the "tutti-frutti" effect if they need to repeat.
Sky textures taller than 128 pixels can also be used. If a sky texture is at least 200 pixels tall, it will never be stretched out of proportion to fill the screen when you look up because it doesn't have to. Please note that the texture itself must be this tall (not the patch it contains) to avoid the stretching of the sky. WinTex cannot create textures taller than 128 pixels, so you will need to use another tool such as DeeP97 to create them.