Re: width of propertized string

[Richard M Stallman]

    > Given a propertized string, how would one find out what its (pixel)
    > dimensions are going to be?

    Display it, measure its size.

That is not adequate when you want to choose other text based the size
of this text.  There needs to be a way to compute the size before
displaying the text.

    The font to be used depends on the frame where it's displayed, so the
    size of the text needs to be considered in the context where it'll
    be displayed.

Indeed, and this way could involve specifying the frame as well as a position
in a buffer.