Most of my CSS/HTML files are UTF-8, due to working with them in Aptana, which is set to UTF-8 by default. When working with the same files in the new editor in Domino Designer 8.5, the default format is Cp1252, which messes up my mystical Norwegian characters, æ, ø and å.
To change this, open Preferences for the designer. Goto General -> Workspace. Set Text file encoding to UTF-8 (or UTF-16 if need be).