pirx yup I agree it's not intuitive, I've been meaning to revise it but the problem is a little more awkward than it's face value. Depending on the size of the text file it can take a noticeable amount of time to save it, so saving after each change would make the editor really laggy and saving on an interval adds the risk of people occasionally seeing the old version.
There's been a few suggestions to add a manual "save" button for these 2 editors, but I don't think this really solves the problem and it would mean having 2 save buttons on screen at once ( one for the editor and one for the project ), which would be confusing to say the least.
If I can fix the "isChanged" indication then UX wise it will work as if every change is saved, but in reality will only save when it's needed.