[Rd] proposal: 'dev.capabilities()' can also query Unicode capabilities of current graphics device

[Martin Maechler]

>>>>> Trevor Davis 
>>>>>     on Thu, 31 Aug 2023 13:49:03 -0700 writes:

    > Hi,

    > It would be nice if `grDevices::dev.capabilities()` could also be used to
    > query whether the current graphics device supports Unicode.  In such a case
    > I'd expect it to return `FALSE` if `pdf()` is the current graphics device
    > and something else for the Cairo or Quartz devices.

    > Thanks,
    > Trevor

I agree in principle that this would be useful new feature for
dev.capabilities()

However, pdf()   *does*  support  Unicode.

The problem is that some pdf *viewers*,
notably `evince` on Fedora Linux, for several years now,
do *not* show *some* of the UTF-8 glyphs because they do not use
the correct fonts {which *are* on the machine; good old `xpdf`
does in that case show the glyphs}.

Martin