[Rd] Xll.options().

[Rolf Turner]

This question seemed to me to be more appropriate for r-devel
than for r-help.  My apologies if this is not the case.

Recently I installed ``cairo'' on my lap-top so that I could make
use of the (newish) polypath() function, with on-screen graphics.
(The polypath() function does not work with X11(type="Xlib").)

The installation went smoothly, X11(type="cairo") works just fine,
and polypath() works just fine.

However the default "type" for X11() remains "Xlib" rather than
"cairo".

The help for X11.options() says (in respect of "type"):

     Default "cairo" where available and reliable, otherwise "Xlib".

Now "cairo" is definitely available:

 > capabilities()["cairo"]
     cairo
      TRUE

and moreover it works (just fine!) when I do X11(type="cairo")
explicitly.

I know that I can set the default to be "cairo" in my .Rprofile, but
I am curious as to why "cairo" does not become the default automatically.

Is it the case that "cairo" is ``not reliable'' under my system?  It 
***seems***
to be reliable.

 > sessionInfo()
R version 2.13.1 Patched (2011-07-17 r56404)
Platform: i686-pc-linux-gnu (32-bit)

locale:
  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
  [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
  [5] LC_MONETARY=C              LC_MESSAGES=en_US.UTF-8
  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
  [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

attached base packages:
[1] datasets  utils     stats     graphics  grDevices methods   base

other attached packages:
[1] misc_0.0-13     gtools_2.6.2    spatstat_1.23-1 deldir_0.0-15
[5] mgcv_1.7-6      fortunes_1.4-2  MASS_7.3-13

loaded via a namespace (and not attached):
[1] grid_2.13.1        lattice_0.19-30    Matrix_0.999375-50 nlme_3.1-101

     cheers,

         Rolf Turner