R help - Oct 2009 - storing initial path for tkgetOpenFile

Hi,

I'd like to store the path from which I opened a file with tkgetOpenFile and
use it as the initial path for the next function call of tkgetOpenFile. What 
is the best way of doing this? The following works fine on my Windows 
computer. However, I'm not sure if it works on other platforms.

getFilename <- function (filename)
{
   if (missing(filename)) {
     temp.file <- paste(sub(".{10}$", "", tempdir()),
                        'getFilename.tmp', sep = "")
     if (file.exists(temp.file)) {
       initialdir <- readLines(temp.file, warn = FALSE)
     } else {
        initialdir <- getwd()
     }
     suppressMessages(require(tcltk, quietly = TRUE))
     filename <- tclvalue(tkgetOpenFile(filetypes = "{{All} {.*}}",
                                          initialdir = initialdir))
     if (!nchar(filename)) {
       stop('aborted')
     }
     if (initialdir != dirname(filename)) {
       cat (dirname(filename), file = temp.file)
     }
   }
   filename
}

getFilename()