Re: XTerm char-width handling

[Markus Kuhn <Markus.Kuhn@cl.cam.ac.uk>]

I very much agree with Otfried's recommendation of keeping cursor
control of xterm strictly tied to cell coordinates and not to character
coordinates. This gives a very simple and clean interface and editor
developers will know exactly what to expect.

It it is indeed a useful analogy to think of the charcell matrix as the
pixel coordinates one would use with a proportional font, just that in
our case, the character widths are restricted to either 1 or 2 "pixels".

The cursor should probably only become wide if it is positioned on the
left half of a double-cell character. If it gets accidentally positioned
onto the right half of a character, this indicates most likely some
application error, and it is a good idea to change the shape of the
cursor in that case. The cursor shouldn't look identical if it is
positioned on the left and right half, to assist in debugging.

Markus

-- 
Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org,  WWW: <http://www.cl.cam.ac.uk/~mgk25/>

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