[R] par("plt") behaving inconsistely? bug?

[Murat Tasan]

Hi all -- I just encountered a behavior that I believe has changed
from previous versions, though I haven't chased back the last version
that behaves as my existing code expects quite yet.
Perhaps this is a bug, though perhaps I'm missing a subtle detail
somewhere in the documentation...

Here's some code that works as expected (in R 3.1.1):

########################################
pdf()
plot.new()

original_plt <- par("plt")

plt_1 <- c(original_plt[1],
           original_plt[1] + (original_plt[2] - original_plt[1]) / 2,
           original_plt[3],
           original_plt[3] + (original_plt[4] - original_plt[3]) / 2)
par("plt" = plt_1)
plot.window(xlim = c(0, 1), ylim = c(0, 1))
box()
plt_2 <- c(plt_1[2],
           original_plt[2],
           plt_1[4],
           original_plt[4])
par("plt" = plt_2)
plot.window(xlim = c(0, 1), ylim = c(0, 1))
box()
par("plt" = original_plt)
box(lty = 2)
dev.off()
########################################

This will draw 3 boxes... one in the lower left corner (specified by
plt_1), one in the top right corner (specified by plt_2), and one
dotted box around the full plot box (original_plt).

Now, if you replace the first two box() calls by: rect(0, 0, 1, 1),
only the lower-left rectangle is drawn.
If you _add_ rect(0, 0, 1, 1) after each box() call, all boxes and
rectangles are correctly drawn.

It seems that after setting plt once, subsequent plt alterations put
the device into a state that will permits drawing of _some_ things
(e.g. box()), but not other things (e.g. rect, lines, points).

A kludge to fix this is to call box(col = "white")... but that's quite
the kludge, indeed!
Axis() works just like box(), too... but I haven't exhausted which
drawing functions work and which don't.

I'd classify this is a bug, but I thought I'd check here first.
I've also only checked this so far with the pdf() device, so I don't
know if it is somehow device-specific.

I detected this because some existing code (that worked on some
earlier version of R, sorry that I don't know which one yet...) has
suddenly stopped working!

Cheers!

-murat