title: unable to print the label and outline box of a cluster subgraph in graphviz
body: <p>I am a newbie to graphviz and the DOT language. I was trying out generating graphs with cluster subgprahs. However, when I have clusters, each with node positions exactly specified in the script, graphviz does not generate the outline boxes or the labels for the clusters!
  Specifically, if I have the following DOT script:</p>
  
  <pre><code>digraph G{
  subgraph cluster0{
  label="Cluster 0"
  a-&gt;b
  }
  subgraph cluster1{
  label="Cluster 1"
  c-&gt;d
  }
  }
  </code></pre>
  
  <p>then the graph generated is:
  <img src="https://i.stack.imgur.com/oGndv.png" alt="Graph generated with clusters when nodes positions are not specified by the user"></p>
  
  <p>However, with the following DOT script, in which I specify the node positions of the 4 nodes exactly:</p>
  
  <pre><code>digraph G{
  subgraph cluster0{
  label = "Cluster 0"
  a[pos="10,200"]
  b[pos="100,200"]
  a-&gt;b
  }
  subgraph cluster1{
  label = "Cluster 1"
  c[pos="10,100"]
  d[pos="100,100"]
  c-&gt;d
  }
  }
  </code></pre>
  
  <p>The graph generated is:
  <img src="https://i.stack.imgur.com/ZTEHO.png" alt="Graph generated with clusters when nodes positions are specified by the user"></p>
  
  <p>Notice that in this case, neither the outline box for the clusters nor the labels for the clusters are printed!! In this case, there is a clear demarcation between the 2 clusters as you can see - the clusters don't overlap, so in principle graphviz should not have a problem showing them, am I right?</p>
  
  <p>How can I tell graphviz to draw the cluster outline boxes and labels no matter what?
  Any help in this will be greatly appreciated!!</p>
  
  <p>Thanks!</p>