[R] locator() via tcltk

[Sebastian Luque]

Hello,

I'm trying to write a function using tcltk to interactively modify a plot
and gather locator() data. I've read Peter's articles in Rnews, the help
pages in tcltk, http://bioinf.wehi.edu.au/~wettenhall/RTclTkExamples/,
plus a post in R-help sometime ago, but haven't found a solution.
The idea goes something like this:

require(tcltk)
testplot <- function() {
  getcoords <- function(...) {
    locator(5)
  }
  x <- 1:1000
  y <- rnorm(1000)
  plot(x, y)
  base <- tktoplevel()
  loc.pts <- tkbutton(base, text = "Get coordinates", command = getcoords)
  quit.but <- tkbutton(base, text = "Quit",
                       command = function() tkdestroy(base))
  tkpack(loc.pts, quit.but)
}

I'd like testplot to return the value from getcoords. The "Get
coordinates" button seems to be correctly calling getcoords, and locator
is doing its job, but I don't know how to store its value. Any help is
very much appreciated.

Regards,
Sebastian
-- 
Sebastian P. Luque