drawNestedBars<-function(x,start,end,shrink=0.1,errbars=FALSE,
 intervals=TRUE,col=NA,labelcex=1,lineht=NA,showall=TRUE,Nwidths=FALSE,
 barlabels=NULL,showlabels=TRUE,arrow.cap=NA) {

 barcol<-ifelse(is.list(col),col[[1]],col)
 # may be only one bar per call
 if(!is.null(x[[1]][[1]]) && (showall || length(x[[1]])==1))
  rect(start,0,end,unlist(x[[1]][[1]]),col=barcol)
 if(showlabels && !is.null(x[[1]][[1]])) {
  if(!is.null(barlabels)) barlabel<-barlabels[[1]]
  else
   barlabel<-names(x[[1]][[1]])
  labely<--lineht*length(x[[1]])
  # zero length bar label suppresses this
  if(nchar(barlabels[[1]][1])) {
   par(xpd=TRUE)
   segments(c(start,end,start),c(0,0,labely),c(start,end,end),rep(labely,3))
   boxed.labels((start+end)/2,labely,barlabel,ypad=1.4,
    bg=ifelse(is.na(barcol),"white",barcol),cex=labelcex)
   par(xpd=FALSE)
  }
 }
 if(errbars && length(x[[1]])==1)
  dispersion((start+end)/2,x[[1]][[1]],x[[2]][[1]],x[[3]][[1]],
   intervals=intervals,arrow.cap=arrow.cap)
 # remove the first component of each element of x displayed above
 for(xcomp in 1:length(x)) x[[xcomp]][[1]]<-NULL
 # if there are any more bars to display, set up the call
 if(length(x[[1]])) {
  # number of values in the new first component of x 
  nvalues<-length(unlist(x[[1]][[1]]))
  # drop the color of the last bar
  if(is.list(col)) col[[1]]<-NULL
  # drop the top level barlabels if present
  if(!is.null(barlabels) && length(barlabels) > 1) barlabels[[1]]<-NULL
  # width of all the spaces between the next group of bars
  barspace<-(end-start)*shrink
  # width of the bars
  if(Nwidths)
   barwidth<-((end-start)-barspace)*x[[4]][[1]]/sum(x[[4]][[1]])
  else barwidth<-rep(((end-start)-barspace)/nvalues,nvalues)
  # width of each space between bars
  barspace<-barspace/(nvalues+1)
  # step through the values for this group of bars
  for(nextval in 1:nvalues) {
   newx<-list()
   # slice the x arrays for this set of values
   for(xcomp in 1:length(x))
    newx[[xcomp]]<-lapply(x[[xcomp]],sliceArray,nextval)
   newbarlabels<-barlabels
   start<-start+barspace
   newcol<-col
   if(is.list(col)) newcol[[1]]<-col[[1]][nextval]
   if(!is.null(barlabels)) newbarlabels[[1]]<-barlabels[[1]][nextval]
   drawNestedBars(newx,start,start+barwidth[nextval],shrink=shrink,
    errbars=errbars,col=newcol,labelcex=labelcex,lineht=lineht,
    showall=showall,Nwidths=Nwidths,barlabels=newbarlabels,
    showlabels=showlabels,arrow.cap=arrow.cap,intervals=intervals)
   #else print(newx)
   start<-start+barwidth[nextval]
  }
 }
}