This doesn't have anything to do with Stack Exchange pages, it's a browser thing and mostly a very good thing.

You can see that the page isn't doing it by:

1. Disable all javascript on your browser.
2. (Re)load an appropriate Stack Exchange page (or any long page with a <textarea>).
3. Focus the textarea for keyboard input but use the mouse to scroll it out of view.
4. Start typing.
5. The browser will then scroll the textarea into view. (Not verified on IE.)
6. The page can't be doing it, since all javascript is shut off.

Possible workaround:
You can write a userscript or browser extension that applies position: fixed; to the WMD textarea and shrink it to a smaller fixed box on the screen.

That way, when you type, it will not change the scroll-position of the rest of the page/screen.

With a little extra work, the script could also check for inserted/changed "preview" elements, and attempt to keep them sensibly scrolled in view.

This doesn't have anything to do with Stack Exchange pages, it's a browser thing and mostly a very good thing.

You can see that the page isn't doing it by:

1. Disable all javascript on your browser.
2. (Re)load an appropriate Stack Exchange page (or any long page with a <textarea>).
3. Focus the textarea for keyboard input but use the mouse to scroll it out of view.
4. Start typing.
5. The browser will then scroll the textarea into view. (Not verified on IE.)
6. The page can't be doing it, since all javascript is shut off.

Possible workaround:
You can write a userscript or browser extension that applies position: fixed; to the WMD textarea and shrinks it to a smaller fixed box on the screen.

That way, when you type, it will not change the scroll-position of the rest of the page/screen.

With a little extra work, the script could also check for inserted/changed "preview" elements, and attempt to keep them sensibly scrolled in view.

This doesn't have anything to do with Stack Exchange pages, it's a browser thing and mostly a very good thing.

You can see that the page isn't doing it by:

1. Disable all javascript on your browser.
2. (Re)load an appropriate Stack Exchange page (or any long page with a <textarea>).
3. Focus the textarea for keyboard input but use the mouse to scroll it out of view.
4. Start typing.
5. The browser will then scroll the textarea into view. (Not verified on IE.)
6. The page can't be doing it, since all javascript is shut off.

Possible workaround:
You can write a userscript or browser extension that applies position: fixed; to the WMD textarea and shrinks it to a smaller fixed box on the screen.

That way, when you type, it will not change the scroll-position of the rest of the page/screen.

With a little extra work, the script could also check for inserted/changed "preview" elements, and attempt to keep them sensibly scrolled in view.

This doesn't have anything to do with Stack Exchange pages, it's a browser thing and mostly a very good thing.

You can see that the page isn't doing it by:

1. Disable all javascript on your browser.
2. (Re)load an appropriate Stack Exchange page (or any long page with a <textarea>).
3. Focus the textarea for keyboard input but use the mouse to scroll it out of view.
4. Start typing.
5. The browser will then scroll the textarea into view. (Not verified on IE.)
6. The page can't be doing it, since all javascript is shut off.

Possible workaround:
You can write a userscript or browser extension that applies position: fixed; to the WMD textarea and shrink it to a smaller fixed box on the screen.

That way, when you type, it will not change the scroll-position of the rest of the page/screen.

With a little extra work, the script could also check for inserted/changed "preview" elements, and attempt to keep them sensibly scrolled in view.