Thx for your input, Ginsengelf.

Sure, I'd have to manage a list of editable QTextFragments somehow. The somehow is my question; I'd rather not do this explicitly. As for the readonly, once I have that list, to filter edit events shouldn't be a big deal. The highlighting part troubles me most for now.

Downloaded the QtCreator sources and tried to extract what I need. However I am completely overwhelmed by the sheer size, just as I feared in the first place.

Still open for more...