title: Not able to order fill colors as desired
body: <p>I need to produce a plot with two separate geom_area commands, in order to draw some time series above and some below the zero line. Here is a simple example:</p>
  
  <pre><code>library("reshape2")
  library("ggplot2")
  
  d &lt;- as.data.frame(t(read.table(sep=";",header=F,row.names=1,text="
  year;1999;2000;2001;2002;2003;2004;2005;2006;2007;2008;2009;2010;2011;2012
  primary balance;-5.63;-11.88;-15.37;-18.3;-20.09;-21.45;-21.87;-23.25;-26.98;-29.56;-28.92;-28.46;-29.64;-32.61
  snow-ball effect;1.61;0.81;2.67;4.99;7.23;8.02;9.45;9.6;11.01;14.06;22.81;24.41;25.76;26.89
  adjustment;2.83;5.38;6.52;3.93;2.28;2.45;3.94;5.28;4.5;6.73;6.94;7.59;7.73;8.07")))
  dd &lt;- melt(d,id.vars="year")
  dd1 &lt;- subset(dd,variable=="primary balance")
  dd2 &lt;- subset(dd,variable!="primary balance")
  ggplot()+
    geom_area(data=dd1,aes(x=year,y=value,fill=variable,order=variable),alpha=.5)+
    geom_area(data=dd2,aes(x=year,y=value,fill=variable,order=variable),alpha=.5)
  </code></pre>
  
  <p>The plot is:
  <a href="https://i.stack.imgur.com/R5y3f.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/R5y3f.png" alt="plot"></a></p>
  
  <p>Although the order of levels for variable is: (1) "primary balance", (2) "snow-ball effect" and (3) "adjustment", there is now way I can tell ggplot to assign colors and put items in the legend in the correct order.</p>