title: par() options pin and oma in R
body: <p>I'm having a problem using the <code>par</code> option <code>oma</code> to set a plot-wide title, when I have specified plot sizes using <code>pin</code>.  The <code>oma</code> title is way way up (seems outside of the <code>oma</code> range) when <code>pin</code> is used; when <code>pin</code> is commented out (as below) the <code>oma</code> title location is visually appealing.  I've tried rotating the sequence of <code>par</code> options, thinking one might be over-riding the others, but no luck.  Code is below.  Clues appreciated!  Thanks, Tom</p>
  
  <pre><code>par(mfrow=c(1,2)) # 1X2 graphs
  par(oma=c(0,0,5,0))  # top has 5 lines of space 
  par(mar=c(4,4,2,1)+.1)  # margin lines
  #par(pin=c(1.9,1.9))  # plot areas for graphs
  
  # plot 1
  plot(rnorm(n=20),col="olivedrab",pch=19,ylim=c(-2.0,2.0),xlim=c(0,20),ylab="",xlab="")
  mtext("Observation No.",side=1,line=3)
  mtext("Random variate",side=2,line=3)
  mtext("Olivedrab Plot",side=3,line=2,cex=1.5)
  
  # plot 2
  plot(rnorm(n=20),col="olivedrab2",pch=19,ylim=c(-2.0,2.0),xlim=c(0,20),ylab="",xlab="")
  mtext("Observation No.",side=1,line=3)
  mtext("Random variate",side=2,line=3)
  mtext("Olivedrab Plot",side=3,line=2,cex=1.5)
  
  mtext("Army Olive Drab Plots",side=3,line=3,cex=2,outer=TRUE)  # add outer label
  </code></pre>