ggplot(mtcars,aes(x=disp,y=mpg,colour=cyl))+
geom_point()+
opts(
legend.background=theme_rect(fill='red',colour='white')
, panel.background=theme_rect()
)
ggplot(mtcars,aes(x=disp,y=mpg,colour=cyl))+
geom_point()+
facet_grid(vs~.)+
opts(
legend.background=theme_rect(fill='red',colour='white')
, strip.background=theme_rect()
)