[Rd] os x crash using rpanel and tcltk (PR#10495)

[a.robotham at bris.ac.uk]

Hello,
I've recently discovered a persistent issue with rpanel when running
R.app (2.6.1) on Mac OS X 10.4.11. tcltk and rpanel load without any
apparent error, and the interactive panels appear to work as expected,
however upon closing the panels rpanel has created I get catastrophic
errors and R crashes completely. For the most part R manages to crash
with dignity and work can be saved, but sometimes it will crash
straight out. Below is an example of an entire work session (only base
packages loaded) with the crash at the end typical of those
encountered:

> library(tcltk)
Loading Tcl/Tk interface ... done
> library(rpanel)
Package `rpanel', version 1.0-4
type help(rpanel) for summary information
> density.draw <- function(panel) {
+   plot(density(panel$x, bw = panel$h))
+   panel
+ }
> panel <- rp.control(x = rnorm(50))
> rp.slider(panel, h, 0.5, 5, log = TRUE, action = density.draw)

 *** caught bus error ***
address 0x0, cause 'non-existent physical address'

Possible actions:
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace

All packages that are required are up to date, and I can find no
evidence of similar issues from searching the mailing lists. Any
suggestions would be appreciated.

Aaron