Deleting Lone Surrogates

Richard Wordingham richard.wordingham at
Sun Oct 4 16:18:42 CDT 2015

On Sun, 4 Oct 2015 12:30:23 -0700
"Asmus Freytag (t)" <asmus-inc at> wrote:

> If you have a bug that doesn't let you enter a sequence without
> creating a lone surrogate followed by a combining mark, that's a
> bug...

Unfortunately, the bug appears to be in an ill-defined interface in
which I have observed regression even within the BMP.  We've discussed
the ambiguity of 'delete one character' in the context of normalisation
before on this list, and the surest solution seemed to be for the
application to surrender some control of its 'backing store' to the
input method.

It's conceivable that the input methods that are compatible for the BMP
are incompatible in the supplementary planes. For now, I'm going to
have to either work round the problem by using dead keys instead or be
thankful that the application hasn't caught up with Unicode 7.0.


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