The predicate for fixed-width fonts.
if the optionally specified
, or otherwise
the font associated with
, is fixed-width.
fixed-width is not exactly the same as single-width. A fixed-width font with double width characters is dual-width; other fixed-width fonts are single-width.
editor-pane supports variable width fonts on Microsoft Windows, GTK+ and Motif.
CAPI Reference Manual - 15 Dec 2011