Вот метод, использующий library(tcltk)
EntryBox <- function(label = 'Enter', title = 'Entry Box') {
tt <- tktoplevel()
tkwm.title(tt, title)
done <- tclVar(0)
tkbind(tt,"<Destroy>", function() tclvalue(done) <- 2)
result <- tclVar("")
cancel.but <- tkbutton(tt, text='Cancel', command=function() tclvalue(done) <- 2)
submit.but <- tkbutton(tt, text="Submit", command=function() tclvalue(done) <- 1)
tkgrid(tklabel(tt, text=label), tkentry(tt, textvariable=result), pady=3, padx=3)
tkgrid(submit.but, cancel.but, pady=3, padx=3)
tkfocus(tt)
tkwait.variable(done)
if(tclvalue(done) != 1) result <- "" else result <- tclvalue(result)
tkdestroy(tt)
return(result)
}
x <- EntryBox(label = 'Enter a string'); x