[R] How to add the variable name to a qqplot or densityplot in the diagonal of an splom?

[Michael Kubovy]

splom() doesn't complain here, but writes no names in the diagonal  
boxes. What am I missing?
I believe that I need to add something like grid.text(x, ...) to the  
diagonal panel, but I don't know how to get it cycle through the  
column labels. And should
     varname.col = 'blue', varname.cex = 1
be inside the diag.panel() function?

splom(szw[, n], pscales = 0,
     diag.panel = function(x, ...){
         panel.qqmathline(x, ...)
         panel.qqmath(x, ...)
     },
     lower.panel = function(x, y, ...){
         panel.xyplot(x, y, ..., col = 'lightblue')
         panel.loess(x, y, ..., col = 'red')
     },
     upper.panel = function(x, y, ...){
         panel.abline(lm(y~x),...)
         grid.text(round(cor(x, y, use = 'pairwise.complete.obs'), 2),
             x = unit(1, 'mm'),
             y = unit(1, 'npc') - unit(1, 'mm'),
             just = c('left', 'top'),
             gp = gpar(fontsize = 10))
     },
     varname.col = 'blue', varname.cex = 1
)


_____________________________
Professor Michael Kubovy
University of Virginia
Department of Psychology
USPS:     P.O.Box 400400    Charlottesville, VA 22904-4400
Parcels:    Room 102        Gilmer Hall
         McCormick Road    Charlottesville, VA 22903
Office:    B011    +1-434-982-4729
Lab:        B019    +1-434-982-4751
Fax:        +1-434-982-4766
WWW:    http://www.people.virginia.edu/~mk9y/