Re: column int->float diff

[Richard Stallman]

    It's possible that indent.c should look at the glyph matrices, where this 
    information is already spelled out.

I don't think there is any way to determine reliably whether
part of the glyph matrices correspond correctly to the buffer.
So you could only do this when redisplay is up-to-date for the buffer.
At that point, you know the glyph matrices do match the buffer text.

I tend to think it is not worth the trouble of writing special code to
handle that particular case.