A (hopefully) simpler alternative to trellis.par.get/set. This
is deprecated, and the same functionality is now available with
trellis.par.set
lset(theme = col.whitebg())a list decribing how to change the settings of the
current active device. Valid components are those in the list
returned by trellis.par.get(). Each component must itself be
a list, with one or more of the appropriate components (need not
have all components). Changes are made to the settings for the
currently active device only.