[R] Formatting panel borders in lattice package

[Hil Lyons]

Hello all --

I would like to thicken the borders between panels -- or more generally, 
all borders -- in a plot generated using lattice (specifically, 
levelplot).  Something similar perhaps to box() function in graphics. 
I haven't been successful in reviewing available documentation.

The problem stems from using a grayscale colorscheme that puts black 
colors near the borders, thus obscuring them.  Then, another alternative 
would be to somehow inject white space between panels.

In summary:
1) Does anybody know of a good way to increase the line thickness of 
borders in lattice, specifically those separating panels?
2) Does anybody know of a way to separate panels with whitespace?

Advice is very much appreciated.

Thanks,
Hil Lyons
Graduate Student
Univ. of Washington Dept of Statistics