title: Change color of pie chart on drilldown
body: <p>I've a pie chart with drilldown data and like to change the chart.options.colors. Is there a way to replace the whole color array in chart.options.colors on drilldown, and restore the old color array to chart.options.colors on drillup?</p>
  
  <p>Tried to change the array in chart.options.colors and to call redraw(), but it does not work correctly. </p>
  
  <p>Thank you</p>
  
  <p>Torben</p>