title: Combined box-violin plot not aligned
body: <p>I want to graph a distribution along two dimensions using a violinplot with a boxplot in it. The result can be really fascinating, but only when done right.</p>
  
  <pre><code>ToothGrowth$dose &lt;- as.factor(ToothGrowth$dose)
  head(ToothGrowth)
  plot &lt;- ggplot(ToothGrowth, aes(x=dose, y=len, fill=supp)) +
    geom_violin() + geom_boxplot(width=0.1)  + theme(legend.position="none")
  ggsave(filename="Violinboxplot.png", plot, height=6, width=4)
  </code></pre>
  
  <p>This is however what I get:</p>
  
  <p><a href="https://i.stack.imgur.com/TAhK2m.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TAhK2m.png" alt="enter image description here"></a></p>
  
  <p>The boxplots are aligned along the axis belonging to the factor. How can I shift them to be in the center of the violinplots?</p>