[R] focus to tkwindow after a PDF window pop up

[Peter Dalgaard]

Hao Liu wrote:
> Dear All:
>
> I currently have a TK window start a acroread window: However, when the 
> acroread window is open, I can't get back to the TK window unless I 
> close the acroead.
>
> I invoked the acroread window using: system(paste("acroread ",file, sep=""))
>
> anything I can do to make them both available to users?
>   
Tell system() not to _wait_ for command to complete.