Don't create a new graphics device on exist in ggsave(). Closes #2363.

Author: clauswilke

NEWS.md

@@ -6,6 +6,9 @@
 *   Data is no longer internally reordered when faceting. This makes it safer to
     feed data columns into `aes()` or into parameters of geoms or stats. However,
     doing so remains discouraged (@clauswilke).
+    
+*   `ggsave()` now exits without creating a new graphics device if previously
+    none was open (@clauswilke, #2363).
 
 
 # ggplot2 3.0.0

R/save.r

@@ -58,7 +58,7 @@ ggsave <- function(filename, plot = last_plot(),
   dev(filename = filename, width = dim[1], height = dim[2], ...)
   on.exit(utils::capture.output({
     grDevices::dev.off()
-    grDevices::dev.set(old_dev)
+    if (old_dev > 1 ) grDevices::dev.set(old_dev) # restore old device unless null device
   }))
   grid.draw(plot)