I already worked out my issues and found the best thing for my system. I thank you for the suggestions. Normal scaling does not look good with ddraw to me. ddraw with advinterp2x clears up the ddraw fuzziness enough to make it very good looking.

Do you mean the formatting of the config file is wrong, as if all the text is on one long (wrapped) line?

I think GOG's DOSBox setup tool replaces the linefeeds in the text with unix-type linefeeds, which e.g. Windows Notepad doesn't identify (hence, Notepad doesn't know where a new line starts, but shows everything in one line).

If this is the problem, open the config (text) file with Wordpad instead, it should display it correctly. After you save it with Wordpad, you can also see it ok with Notepad (ie. Wordpad seems to save it with Windows linefeeds).

I was under the impression that if you use any of the scalers, then the windowresolution setting is disregarded, and e.g. a 3x scaler would only give me a 960x600 window, which is vertically too small for my 1600x900 screen. Maybe I was wrong then.

I'll experiment with it. My main priority is to get the game window to the correct size, and then worry about if the pixels are exactly square or whatever. As long as they are not as badly distorted as in stretching e.g. a 4:3 image to 16:9, that I don't like.

EDIT: Ok I set it now to ddraw with normal3x, and leaving the windowresolution to 1152x864. I seem to still get the correct window size so I guess this is fine then. I can't tell if the graphics are any better (or worse) than before, same blockiness as 320x200 DOS games normally are to my eyes. :) I experimented it with TES Arena.

I'd recommend using Notepad++ instead, as wordpad might by default try to use rtf or another format, and add junk formatting to the file that is useless. It also contains a decent regex search/replace engine so that's useful :)

Just in case someone wants to go by with whatever tools Windows provides by default, e.g. working on someone else's PC... Yes it is important to remember to save the text file as a plain text file in Wordpad, and not some other format.

I think that's only with some output modes, like overlay. In my experience ddraw sticks to the specified window size. If the distortion you get with overlay and no scaler doesn't bother you then fair enough.
I was replying to timppu. :P