[R] Plot can't forget bad parameters

[Ross Boylan]

When I give plot some bad paramaters, it keeps giving me error messages
forever after.  I think the last time this happened, I even got the
error messages for completely unrelated, non-graphical functions.

Here's a recent example:
> plot(it[[31]][,c(1, 3)], type="b", usr=c(0, 20, -20, 5))
Warning messages: 
1: parameter "usr" couldn't be set in high-level plot() function 
2: parameter "usr" couldn't be set in high-level plot() function 
3: parameter "usr" couldn't be set in high-level plot() function 
4: parameter "usr" couldn't be set in high-level plot() function 
5: parameter "usr" couldn't be set in high-level plot() function 
6: parameter "usr" couldn't be set in high-level plot() function 
> plot(it[[31]][,c(1, 3)], type="b", ylim=c(-20, 5))
Warning messages: 
1: parameter "usr" couldn't be set in high-level plot() function 
2: parameter "usr" couldn't be set in high-level plot() function 
3: parameter "usr" couldn't be set in high-level plot() function 
4: parameter "usr" couldn't be set in high-level plot() function 
5: parameter "usr" couldn't be set in high-level plot() function 
6....

Is this a bug, or have I missed something?
R 1.7.1
-- 
Ross Boylan                                      wk:  (415) 502-4031
530 Parnassus Avenue (Library) rm 115-4          ross at biostat.ucsf.edu
Dept of Epidemiology and Biostatistics           fax: (415) 476-9856
University of California, San Francisco
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