title: scatter3D cex.clab and rgl
body: <p>I am struggling with how to increase the font size of the color key title in an rgl device that shows a plot created using scatter3D() from the plot3D package.  I have included some code below demonstrating that the cex.clab option influences the font size of the color key title in a graphics device but not an rgl device.  I would appreciate any suggestions on how to increase the font size of the color key title in the rgl device too.<br>
  Thanks,
  Dave</p>
  
  <pre><code>library(plot3D); library(plot3Drgl)
  with(quakes, 
    scatter3D(x=long, y=lat, z=-depth, colvar=mag, pch=16, cex=1.5, 
    xlab="longitude", ylab="latitude", zlab="depth, km", 
    clab=c("Richter", "Magnitude"), main="Earthquakes off Fiji", 
    ticktype="detailed", theta=10, d=2, 
    colkey=list(length=0.5, width=0.5, cex.clab=1))
  )
   plotrgl(lighting = TRUE, smooth = TRUE, cex=2)
  
  with(quakes, 
    scatter3D(x=long, y=lat, z=-depth, colvar=mag, pch=16, cex=1.5, 
    xlab="longitude", ylab="latitude", zlab="depth, km", 
    clab=c("Richter", "Magnitude"), main="Earthquakes off Fiji", 
    ticktype="detailed", theta=10, d=2, 
    colkey=list(length=0.5, width=0.5, cex.clab=2))
  )
  plotrgl(lighting = TRUE, smooth = TRUE, cex=2)
  </code></pre>