[Rd] Qt device update

[Deepayan Sarkar]

Hi,

a few days back I had asked for help on a Qt device package. Thanks to
hints from Duncan TL and Thomas Friedrichsmeier, I now have something
more or less functional. For those interested, It can be downloaded
from

http://dsarkar.fhcrc.org/R/R-Qt.html

I have a couple of related questions. First, dev.interactive(), used
in example() and many demo()-s to decide if the current device is
interactive, is currently implemented as:

> dev.interactive
function (orNone = FALSE)
{
    iDevs <- c("X11", "GTK", "gnome", "quartz", "windows", "JavaGD")
    interactive() && (.Device %in% iDevs || (orNone && .Device ==
        "null device" && getOption("device") %in% iDevs))
}

This makes it impossible for new devices to be treated as interactive.
Perhaps it would be  better to change this to something like

    iDevs <- c("X11", "GTK", "gnome", "quartz", "windows", "JavaGD",
               getOption("interactive.devices"))

so that packages can set an option to be included in this list.

Second, can someone explain the details of what happens when a symbol
font is requested (with font=5 or with plotmath stuff)? demo(plotmath)
seems to work on a machine with LANG=en_US (I don't know what encoding
this means, probably latin1), but some symbols don't work on my
desktop which has en_US.UTF-8. Presumably, this means I have to
interpret the encoding differently, but what exactly is the rule? Is
it enough to treat it as latin1? Some devices have a lot of code
dealing with encodings, and I want to make sure I understand the
issues before I go off on a wild goose chase.

-Deepayan