I wasn't using diffs, my editor directly represented everything as patches, to the extent it exists at all. Much easier to do in some GUI environments than from a web browser.
Of course one of the issues is that a lot of stuff comes down to details. Working in a browser is a hell of a constraint, I wouldn't dream of writing a collaborative editor in a browser. (Not because it's impossible, but because that's an amount of stress I don't need in my life. Obviously it's possible.) It would be interesting to talk to the people involved about the issues, but I suppose that's almost always true.
(BTW, this is me interested in someone who has actually done the stuff I've only designed and curious about the exact details to a fairly deep level about the actual issues they encountered and stuff, as partially indicated in my "to the extent it exists at all" above. I am not trying to tell anyone what they should have done, I'm just chewing the fat as an interested party who stands to learn some interesting-to-me-things. I'm not in a position to tell implementors anything. As usual, tone can be hard to convey in text.)
Of course one of the issues is that a lot of stuff comes down to details. Working in a browser is a hell of a constraint, I wouldn't dream of writing a collaborative editor in a browser. (Not because it's impossible, but because that's an amount of stress I don't need in my life. Obviously it's possible.) It would be interesting to talk to the people involved about the issues, but I suppose that's almost always true.
(BTW, this is me interested in someone who has actually done the stuff I've only designed and curious about the exact details to a fairly deep level about the actual issues they encountered and stuff, as partially indicated in my "to the extent it exists at all" above. I am not trying to tell anyone what they should have done, I'm just chewing the fat as an interested party who stands to learn some interesting-to-me-things. I'm not in a position to tell implementors anything. As usual, tone can be hard to convey in text.)