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

[Hao Liu]

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?

Thanks
Hao