title: xlsxwriter can not make the chart wider
body: <p>I have create a chart by calling</p>
  
  <p>worksheet.insert_chart(chart_row, chart, {'x_scale': 2, 'y_scale': 1})</p>
  
  <p>it is a stacked type.</p>
  
  <p>I want to make the chart horizontal wider, I tried to change x_scale to a big value, it does not do anything to the chart. when I changed it to 0.5, the chart does shrink. it looks like 1, 2, 3,4 value do not make any impact the chart.
  Any ideas?</p>
  
  <p>Thanks</p>