Quartz questions

I'm running R 2.3.1 on OS 10.4.7 with R GUI 1.17-pre (3343).

1. args(quartz) says it defaults to 5x5 inches i.e. 360x360 pixels. 
But I find it gives 6x6 (432x432) instead, and the width and height 
arguments are ignored.

2. Simon recently added a name to the quartz window as the first 
argument. How do I make an inactive window called "fred" the active 
window? If I repeat quartz("fred") it creates another window of the 
same name.

3. I have two identical G4 setups, at home and at work, but quartz 
graphics work differently on them. On the work machine graphs look 
grainy on moderate magnification, whereas the same graphics on the 
home machine look fine. I can't currently provide chapter and verse 
for this, but my question is what (if anything) in the R setup on 
the two machines might explain such a difference in behaviour.

Thanks,
Tim Cole