title: Scatter3d error in R
body: <p>Everytime I use scatter3d, I include the following libraries:</p>
  
  <pre><code>library(rgl)
  library(Rcmdr)
  </code></pre>
  
  <p>but when I load those libraries, I get the following message:</p>
  
  <pre><code>Loading required package: tcltk
  Loading Tcl/Tk interface ... done
  Loading required package: car
  Loading required package: MASS
  Loading required package: nnet
  Loading required package: survival
  Loading required package: splines
  
  Rcmdr Version 1.7-0
  
  
  Attaching package: 'Rcmdr'
  
  The following object(s) are masked from 'package:tcltk':
  
      tclvalue
  
  Warning message:
  In fun(...) : Can't find a usable tk.tcl in the following directories: 
      /System/Library/Frameworks/Tcl.framework/Versions/8.5/Resources/Scripts/tk8.5 /System/Library/Frameworks/Tcl.framework/Versions/8.5/Resources/Scripts/tk8.5/Resources/Scripts /System/Library/Frameworks/Tcl.framework/Versions/8.5/Resources/tk8.5 /System/Library/Frameworks/Tcl.framework/Versions/8.5/Resources/tk8.5/Resources/Scripts ./lib/tk8.5 ./lib/tk8.5/Resources/Scripts ~/Library/Tcl/tk8.5 ~/Library/Tcl/tk8.5/Resources/Scripts /Library/Tcl/tk8.5 /Library/Tcl/tk8.5/Resources/Scripts /System/Library/Tcl/tk8.5 /System/Library/Tcl/tk8.5/Resources/Scripts /System/Library/Tcl/8.5/tk8.5 /System/Library/Tcl/8.5/tk8.5/Resources/Scripts ~/Library/Frameworks/tk8.5 ~/Library/Frameworks/tk8.5/Resources/Scripts /Library/Frameworks/tk8.5 /Library/Frameworks/tk8.5/Resources/Scripts /System/Library/Frameworks/tk8.5 /System/Library/Frameworks/tk8.5/Resources/Scripts ./library
  
  
  
  This probably means that tk wasn't installed properly.
  </code></pre>
  
  <p>and it plots fine. However, if I run the script a few times, x11 always starts crashing after like the 3rd time (the plot comes up, but when I click on it to expand the window or interact with it, x11 stops responding). What does this mean?</p>