Sample Apllication on Journal of Statistical Software Issue 8, Volume 37, December 2010. RGtk2: A Graphical User Interface Toolkit for R.

RGtk2-Sample.R

library(RGtk2)

mainWin <- gtkWindowNew(show = FALSE)
mainWin["title"] <- "Data Sheet"
mainWin$setDefaultSize(600,600)

cbOpen <- function(widget, window) {
  dialog <- gtkFileChooserDialog("Choose file", window, "open", "gtk-cancel",
                                 GtkResponseType["cancel"], "gtk-open",
                                 GtkResponseType["accept"])
  if(dialog$run() == GtkResponseType["accept"]) {
    df <- read.csv(dialog$getFilename())
    loadFile(df, basename(dialog$getFilename()))
  }
  dialog$destroy()
}
cbSave <- function(widget, window) {
  dialog <- gtkFileChooserDialog("Filename", window, "save", "gtk-cancel",
                                 GtkResponseType["cancel"], "gtk-save",
                                 GtkResponseType["accept"])
  if(dialog$run() == GtkResponseType["accept"]) {
    df <- read.csv(dialog$getFilename())
    loadFile(df, basename(dialog$getFilename()))
  }
  dialog$destroy()
}
cbExit <- function(widget, window) {
  window$destroy()
}

actions <- list(
  list("FileMenu", NULL, "_File"),
  list("Open", "gtk-open", "_Open File", "<control>O", "Open CSV", cbOpen),
  list("Save", "gtk-save", "_Save File", "<control>S", "Save CSV", cbSave),
  list("Exit", "gtk-quit", "E_xit", "<control>X", "Exit", cbExit)
)
action_group <- gtkActionGroup("spreadsheetActions")
action_group$addActions(actions, mainWin)

uiManager <- gtkUIManager()
uiManager$insertActionGroup(action_group, 0)
merge <- uiManager$newMergeId()
# File Menu
uiManager$addUi(merge.id = merge, path = "/", name = "menubar",
                action = NULL, type = "menubar", top = FALSE)
uiManager$addUi(merge, "/menubar", "file", "FileMenu", "menu", FALSE)
uiManager$addUi(merge, "/menubar/file", "open", "Open", "menuitem", FALSE)
uiManager$addUi(merge, "/menubar/file", "save", "Save", "menuitem", FALSE)
uiManager$addUi(merge, "/menubar/file", NULL, NULL, "separator", FALSE)
uiManager$addUi(merge, "/menubar/file", "exit", "Exit", "menuitem", FALSE)

# Toobar
uiManager$addUi(merge, "/", "toolbar", NULL, "toolbar", FALSE)
uiManager$addUi(merge, "/toolbar", "open", "Open", "toolitem", FALSE)
uiManager$addUi(merge, "/toolbar", "save", "Save", "toolitem", FALSE)
uiManager$addUi(merge, "/toolbar", "exit", "Exit", "toolitem", FALSE)

menubar <- uiManager$getWidget("/menubar")
toolbar <- uiManager$getWidget("/toolbar")
mainWin$addAccelGroup(uiManager$getAccelGroup())
statusbar <- gtkStatusbar()
info <- statusbar$getContextId("info")
statusbar$push(info, "Ready")

create_tree_model <- function(df) {
  df <- cbind(rownames = rownames(df), df)
  filter_df <- cbind(filter = TRUE, df)
  model <- rGtkDataFrame(filter_df)
  filter_model <- gtkTreeModelFilterNew(model)
  filter_model$setVisibleColumn(0)
  sort_model <- gtkTreeModelSort(filter_model)
  sort_model
}
create_tree_view <- function(model) {
  tree_view <- gtkTreeView(model)
  rdf <- model$getModel()$getModel()
  sapply(tail(seq_len(ncol(rdf)), -1), function(j) {
    renderer <- gtkCellRendererText()
    column <- gtkTreeViewColumn(colnames(rdf)[j], renderer, text = j - 1)
    column$setSortColumnId(j - 1)
    column$setCellDataFunc(renderer,
                           function(column, renderer, model, iter) {
                             iter <- model$convertIterToChildIter(iter)$child.iter
                             child <- model$getModel()
                             iter <- child$convertIterToChildIter(iter)$child.iter
                             i <- rdf$getPath(iter)$getIndices()[[1]] + 1
                             renderer["text"] <- as.character(rdf[i, j])
                           })
    tree_view$appendColumn(column)
  })
  tree_view$setHeadersClickable(TRUE)
  if(is.null(gtkCheckVersion(2, 10, 0))) tree_view$setGridLines("both")
  tree_view
}
create_entry <- function(model) {
  entry <- gtkEntry()
  gSignalConnect(entry, "activate", function(entry) {
    model[, "filter"] <<- eval(parse(text = entry$text), as.dataframe(model))
  })
}

notebook <- gtkNotebook()
notebook$setTabPos("bottom")

vbox <- gtkVBox(homogeneous = FALSE, spacing = 0)
vbox$packStart(menubar, expand = FALSE, fill = FALSE, padding = 0)
vbox$packStart(toolbar, FALSE, FALSE, 0)
vbox$packStart(notebook, TRUE, TRUE, 0)
vbox$packStart(statusbar, FALSE, FALSE, 0)
mainWin$add(vbox)
mainWin$show()

load_spreadsheet <- function(df, name) {
  model <- create_tree_model(df)
  tree_view <- create_tree_view(model)
  entry <- create_entry(model$getModel())
  hbox <- gtkHBox(TRUE, 3)
  hbox$packStart(gtkLabel("Filter expression:"), FALSE, FALSE, 0)
  hbox$packStart(entry, FALSE, FALSE, 0)
  vbox <- gtkVBox(TRUE, 3)
  scrolled_window <- gtkScrolledWindow()
  scrolled_window$add(tree_view)
  vbox$packStart(scrolled_window, TRUE, TRUE, 0)
  vbox$packStart(hbox, FALSE, FALSE, 0)
  if(missing(name)) name <- deparse(substitute(df))
  notebook$appendPage(vbox, gtkLabel(name))
  statusbar$push(info, paste("Dataset", name, "loaded."))
}
load_spreadsheet(mtcars)

Journal: https://www.jstatsoft.org/article/view/v037i08/v37i08.pdf
Package Manual: https://cran.r-project.org/web/packages/RGtk2/RGtk2.pdf