Redguard on 16:10 screen

[Redguard1]

Since a while i´m finally playing redguard (gog), and at the beginning the game aslo kept its standard 4:3 ratio, but one day (maybe i played around in the dosbox settings) it suddenly decided to strech the image to fullscreen instead of leaving two black areas on the left and right side. i also tried to change this on the dosbox configuratzion program and the edguard launcher, but none of this seems to have an effect. can anyone help me with that?

[Redguard1]

nevermind, i managed to change the settings using "nglide_config.exe" in the dosbox folder (had to set it to my screen resolution)