inst/Examples/ch-tcltk/ex-tcltk-wm-delete-window-event.R

In jverzani/ProgGUIinR: support package for "Programming Graphical User Interfaces in R"

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### code chunk number 61: BasicContainers.Rnw:119-125
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## set up window etc. for example
library(tcltk)
window <- tktoplevel()
tkwm.title(window, "Simple text entry example")
entry <- tktext(window)
tkpack(entry)


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### code chunk number 62: example-wm-delete-window
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tkwm.protocol(window, "WM_DELETE_WINDOW", function() {
  modified <- tcl(entry, "edit", "modified")
  if(as.logical(modified)) {
    response <- 
      tkmessageBox(icon = "question",
                   message = "Really close?",
                   detail = "Changes need to be saved",
                   type = "yesno",
                   parent = window)
    if(as.character(response) == "no")
      return()
  }
  tkdestroy(window)                     # otherwise close
})