[R] HowTo get callback on destroy of grDevices::windows()

[rrichte2 at fh-lausitz.de]

  I'm build with the usage of the tcltk/tcltk2 package a gui which is 
started with rscript.exe. At this gui the user is able to open and close 
plot windows.

Now I'm looking for a way that a r function is called when a 
grDevices::windows window is closed.
Is there a way to attach a callback function or so, which would be 
triggert if the user click at close of the grDevices::window?

My workarround is to check continues the open windows with the tcl 
command after, but it's no good workarround.

thanks
roland