R help - Dec 2008 - par(mfrow = ) resets par('cex'), not reduces it

Hello group!

I use R 2.8.0 . I've just found out that par(mfrow =) *resets* par
('cex'), not reduces it as documented. To reproduce:

par(cex = 0.5)
par(mfrow = c(2, 2))
print(par('cex'))

It outputs 0.83, not 0.415 as expected.

Particularly such a behavior makes plot.acf effectively ignore par
('cex') value for multivariate case. I guess there are more situations
where the documented behavior would be more appropriate.

I think it is bug in par implementation not in documentation. Could
anyone comment on this?

Andrey