Dear All: The question: How do I check for existance of the GUI, instead of checking the variable of the GUI? I created a log window for several applications, they will check for the existance of log window, if it exists, append output to it, otherwise, create log window and insert to it. What I found out is that if I close the X window of the GUI, the variable logwin still exists, confuse arises to other components that are supposed to use the GUI. create.log.win <- function(inputtext){ if(exists(is.null("logwin"))) {return} else { logwin <<- tktoplevel() logtext <<- tktext(logwin, bg="white") tkwm.title(logwin," Log Window") loglabel <- tklabel(logwin, text="Logging Analaysis Information") tkgrid(loglabel) tkgrid(logtext) if (is.matrix(inputtext)) { for (i in 1:nrow(inputtext)) tkinsert(logtext, "end",paste(paste(inputtext[i,],collapse=" "),"\n",sep="")) } else tkinsert(logtext, "end",paste(inputtext,"\n",sep="")) export_button <- tkbutton(logwin, text = "Export Log", command=savelog) tkgrid(export_button) } } -- I understand I should bind a function to remove the varialbe with a close button, however, we can't stop users from closing window just by clicking on the upper right corner. How do I check for existance of the GUI, instead of the variable? Thanks