[R] Background color of symbols in xyplot

[Sébastien]

Dear R-users,

I am using plot symbols given by pch=21:25 in a xyplot. The background 
color of these symbols can be defined by 'fill' in the panel argument, 
however I have a hard time to find how to define the same background 
color in the key. I tried different options like using the auto.key 
argument and modifying the par.settings, or using normal key argument 
plus 'fill', 'bg' or 'background'... nothing seems to do I want. What 
should I change in the following code to make it work ?

key=list(space="bottom",
             points = list(pch = 21:25,
                          col = 32,
                          bg=15),
             text=list(mylegend)),


Thank in advance

Sebastien

PS: cheng