[R] How do I change which R Graphics Device is active?

[Mark Knecht]

Hello,
   If I execute

X11()
plot( stuff )
X11()
plot( other stuff)

then at this point I have two windows with plots and the second
graphics window is active. I don't see the devices using ls().

1) Without destroying the second window how do I make the first window
active again?
2) How do I destroy a specific window when I'm done with it?
3) Is there some generic way to understand what windows are out there
at any given time or do I need to create some sort of list and keep
track of it myself?

In general I'd like to have 4 or 5 windows and be able to switch and
update individual plots as the needs arise. Is there a way to name
these devices/windows? I don't see any examples of this sort of thing
in the help file. Maybe there's a different add-on package I don't yet
know about?

Thanks,
Mark