[R] tweaking forest plot (metafor package)

[eesteves at ualg.pt]

Dear All,

I'm having trouble tweaking a forest plot made using the R  
meta-analysis package metafor. I did the analysis based upon the  
correlation coeff from studies and plotted the corresponding forest  
plot easily

> q2<-rma(yi,vi,mods=cbind(grupo),data=qim)
> q2
> forest (q2,transf=transf.ztor,digits=3, ... ,alim=c(0,1),refline=.5)
> text(-1.55,42,"Espécie [refª]",pos=4,font=2)

I'd like to subdivide the "table" by the moderator 'grupo' - i.e.  
create the necessary spacings in the list of studies to accommodate  
the moderator statistics (cf.  
http://rgm2.lab.nig.ac.jp/RGM2/func.php?rd_id=metafor:addpoly.default).

My main issue is that I cannot really understand how the function  
(forest()) really uses space; specifically, how to use the parameters  
'xlim', 'ylim' and 'rows' in the function? how can I change the scale  
from 0-1 to 0.5-1?

Hopefully I've made myself (relatively) clear but... Thanks.

Eduardo Esteves