title: JFreeChart : obtain data source value on mouse click
body: <p>I have a JFreeChart instance that displays process memory status, initialized as follows:</p>
  
  <pre><code>m_data = new TimeSeriesCollection();
  TimeSeries vmsize = new TimeSeries("VMSize");
  TimeSeries resident = new TimeSeries("Resisdent");
  TimeSeries shared = new TimeSeries("Shared memory");
  TimeSeries code = new TimeSeries("Code");
  TimeSeries data = new TimeSeries("Data");
  m_data.addSeries(vmsize);
  m_data.addSeries(resident);
  m_data.addSeries(shared);
  m_data.addSeries(code);
  m_data.addSeries(data);
  JFreeChart chart = ChartFactory.createTimeSeriesChart("Memory usage", "Time", "Size", m_data, true, true, false);
  m_chart = new ChartPanel(chart);
  </code></pre>
  
  <p>Later I add values to each TimeSeries in the TimeSeriesCollection. I would like to somehow know - when the user clicks on the Chart - either what time associated with that columm, or even better - what is the index of the value.</p>
  
  <p>I looked at the JFreeChart and ChartMouseListener classes, but I could not figure out how to do that (also the documentation of JFreeChart is annoyingly scarce, I guess they are trying to get people to buy their developer's guide).</p>