library(gWidgets)
library(gWidgetstcltk)
win <- gwindow("Tab delimited file upload example")
grp_name <- ggroup(container = win)
lbl_data_frame_name <- glabel(
  "Variable to save data to: ",
  container = grp_name
)
txt_data_frame_name <- gedit("dfr", container = grp_name)
grp_upload <- ggroup(container = win)
btn_upload <- gbutton(
  text      = "Upload tab delimited file",
  container = grp_upload,
  handler   = function(h, ...)
  {
    # TODO!
  }
)
use_comma_for_decimal <- function()
{
  unname(Sys.localeconv()["decimal_point"] == ",")
}

chk_eurostyle <- gcheckbox(
  text      = "Use comma for decimal place",
  checked   = use_comma_for_decimal(),
  container = grp_upload
)

status_bar <- gstatusbar("", container = win)

function(h, ...)
{
  gfile(
    text    = "Upload tab delimited file",
    type    = "open",
    action  = ifelse(svalue(chk_eurostyle), "read.delim2", "read.delim"),
    handler = function(h, ...)
    {
      tryCatch(
        {
          data_frame_name <- make.names(svalue(txt_data_frame_name))
          the_data <- do.call(h$action, list(h$file))
          assign(data_frame_name, the_data, envir = globalenv())
          svalue(status_bar) <-
            paste(nrow(the_data), "records saved to variable", data_frame_name)
        },
        error = function(e) svalue(status_bar) <- "Could not upload data"
      )
    },
    filter = list(
      "Tab delimited" = list(patterns = c("*.txt","*.dlm","*.tab")),
      "All files" = list(patterns = c("*"))
    )
  )
}

lmwidget <- ggenericwidget(lm)