The way I implemented it was by updating the "official" back frame buffer, and compare the update with the visible front buffer. If at any time a write to the back buffer did not result in something that was already in the front buffer, I just copied the back buffer to the front and went on from there.
The only application I use which is still doing something like it
nowadays is `mosh`, and I must say that it is a great feature.
[ It's occasionally "problematic", such as when I type a password before
the prompt appears, so `mosh` doesn't know yet that it shouldn't be
displayed. 🙂 ]
Stefan
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