require(tcltk) || stop("tcltk support is absent") base <- tktoplevel() tkwm.title(base,'Label Test') frm <- tkframe(base) lab <- tklabel(frm,text=" ",width=20) tkpack(frm,lab) res <- matrix(0,10,10) for(i in 1:10){ tkconfigure(lab,text=paste(i)) tcl('update') for(j in 1:10){ z <- rnorm(15000) res[i,j] <- mean(z) } }