title: second axis label is to big when using multiple figure panel
body: <p>I am using standard R graphs and create a figure with two axis.
  Everything is fine until I try to plot <code>par(mfrow=c(4,3))</code>. The label on the right side is always a bit to big... When I plot <code>par(mfrow=c(1,1))</code> everything looks fine.</p>
  
  <pre><code>new_cex &lt;- .75
  pdf(file='jnk.pdf', width=11.69, height=8.27)
  par(mfrow=c(4,3), mar=c(5,4,4,5)+.1)
  for(i in 1:12) {
    x &lt;- runif(10)
    y1 &lt;- runif(10)
    y2 &lt;- runif(10)
  
    plot(1, type="n", xlim=range(x), bty="n", axes=F, cex.lab=new_cex,
         ylim=range(pretty(range(y1))), xlab="Time (hours)", ylab="ABC")
    axis(1, at=x, labels=round(x,2), cex.axis=new_cex, las=2)
    axis(side=2, at=pretty(range(y1)), cex.axis=new_cex, las=2)
    points(x, y1, lwd=2)
    lines(lowess(x, y1), lwd=6)
    par(new=TRUE)
    plot(1, type="n", axes=F, bty="n", xlab="", ylab="", xlim=range(x), ylim=range(y2))
    axis(side=4, at=pretty(range(y2)), cex.axis=new_cex, las=2)
    mtext("CDE",side=4,line=3, cex=new_cex)
    points(x, y2, col=2, lwd=2)
    lines(lowess(x, y2), col=2, lwd=6, lty=2)
  }
  
  dev.off()
  </code></pre>
  
  <p>I used a global <code>new_cex</code> variable and I figured out that in case of <code>mfrow=c(4,3)</code> the label is always a bit bigger. So in general it is changing...</p>
  
  <p>Maybe someone can give it a try, maybe it is a versioning thing... By changing the 3 row to <code>mfrow=c(1,1)</code>, all axis labels will have the same size...</p>