title: ggplot2: Bring one line to the front, but save the colors
body: <p>Consider the following code:</p>
  
  <pre><code>library(ggplot2)
  foo &lt;- data.frame(x=1:10,A=1:10,B=10:1)
  ggplot(melt(foo,id.vars="x"),aes(x,value,color=variable))+geom_line(size=5)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/BitIg.png" alt="enter image description here"></p>
  
  <p>I want to bring the red line (A) to the front, on top of B (see the cross point), while the colors and the order they appear in the legend do not change. Is there any way?</p>