boxplot grouped by two variables: general issue

a) Any plans to implement trellis?

	Yes, in fact work is in progress.  Paul Murrell is working on
	generalized layout facilities which will provide the necessary
	support for multipanel conditioning (and more).  It is probably
	premature to talk about a time frame for this, but can report
	that I have seen trellis-like plots on Paul's screen.

	Of course, layout support is just the low-level part of trellis,
	but I think the higher level parts could come comparatively
	quickly once the layout support is in place.  (Issues are things
	like shingles and banking).

b) Are there any other solutions in R which offer simple trellis
functionality?

	Deepayan Sarkar has been working on modifications to coplot
	to make it more trellis-like.  This could well be placed over
	Paul's layout code at some point.

c) Do you think, attacking these problems leads to

reinventing trellis with

all it's complexity?

If the answers turn out to be c(a=NO,b=NO,c=NO) I would

like  to ask in more

detail:

Is it possible to write plot functions to properly behave

as high level AND

as panel functions?

	I want to look issues like this.  Some kind of partitioning of
	functionality is clearly needed.  It should be possible to
	access plots at a variety of levels

	 (i)	High level,
	 (ii)	Purely computational (no plotting).
		Some methods accept a plot=FALSE argument.

	In addition, it seems like we need:

	 (iii)	an intermediate level which allows the embedding
		of plots within other plots.

	Examples of this last are trellis panels and panels of plots
	superimposed on maps.

Are there any issues that NEED to be addressed beyond 1) to 3) ?
Any recommendations? Any related work in progress? Any volunteers?

	A useful contribution would be a look at how to package the
	functionality of the higher levels of trellis.	There
are general
	issues of compatibility and extension, as well as specific
	functionality that needs to be provided.  The "for the record"
	sections of Cleveland's latest book are a good source for
	the latter.