[R] childNames for xaxis grob (grid package)

[Tobias Verbeke]

Dear list,

Can someone explain why the childNames below
gives

character(0)

instead of the (canonical) names of the children grobs
of the xaxis gTree ?

[1] "major"  "ticks"  "labels"

Many thanks in advance,
Tobias

### minimal example code ###

library(grid)
pushViewport(plotViewport(c(5,4,4,2)))
pushViewport(dataViewport(1:5, 1:5))
grid.points(1:5, 1:5)
grid.xaxis(name = "xa")
grid.get("xa")
childNames(grid.get("xa"))

### sessionInfo() ###

 > sessionInfo()
R version 2.7.1 (2008-06-23)
i486-pc-linux-gnu

locale:
en_US.UTF-8

attached base packages:
[1] grid      stats     graphics  grDevices utils     datasets  methods
[8] base