# A Slider to Control Two Plotting Windows

### Yihui Xie / 2010-09-28

One of my readers asked two weeks ago how to control two graphics windows with the slider in gWidgets. Here is a simple example:

if (!require("gWidgetsRGtk2")) install.packages("gWidgetsRGtk2")
library(gWidgetsRGtk2)
options(guiToolkit = "RGtk2")
graphics.off()
x11()
x11()
dev.set()

gslider(from = 1, to = 100, value = 10,
container = gwindow("Two Plotting Windows"),
handler = function(h, ...) {
n = 10 * svalue(h\$obj)
plot(rnorm(n), main = "the 1st plot")
dev.set()
plot(hist(runif(n)), main = "the 2nd plot")
dev.set()
})


The basic idea is to use dev.set() function to set focus on different graphics devices. After one plot has been drawn, go to the next device to draw the next plot. That’s it.