[R] Lattice: change background of conditioning variable box

[Alex van der Spek]

For publication purposes I need to come up with B&W images (grey codes
allowed). For normal R graphics this presents no problem.

For lattice graphics, I can get everything B&W except for the box in
which the conditioning variables are written per panel.

I have searched the manuals but to no avail. Is there anyone who can
point me in the right direction?

Thanks in advance!
Alex van der Spek