Automatic wrap example aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa :
This expression has automatic wrap, because I did not press return.
As I understand you want Soft Wraps, when long line is wrapped on screen into multiple lines, but still remains as single line in file.
Soft Wraps
on per file basis
View | Active Editor | Use Soft Wraps
for all files by default
Settings/Preferences | Editor | General | Use soft wraps in editor
Right margin setting
There is also
Settings/Preferences | Editor | Code Style | General --> Wrap when typing reaches right margin
But that’s different (it will make actual new line).
UPDATE: In current builds IDE can use separate value for right margin per different “language” — as long as that language has an entry in Code Style settings.
Also keep in mind that any settings from .editorconfig files (if you have such files in your project and EditorConfig plugin is installed & enabled) will override the same from Code Style settings — it’s the nature of the plugin and not a bug (it meant to work this way).
Using EditorConfig support you can configure certain settings that otherwise may not be possible to do via Code Style (e.g. settings for languages/file types that have no separate Code Style entry).