there's a picture near the top showing a line chart overlaid
on a column chart, and the endpoints of the line segments are
centered horizontally within each bar.
There are two code samples later in the page showing similar
charts, but the bars are only half as wide as they are in the first
picture, and the result is that the line segment endpoints coincide
with the right edges of the bar instead of the bar centers.
I'm wondering how to produce a graph like the first picture.
I tried different combinations of columnWidthRatio but nothing
seemed to help. If I add more line series to the examples, the bars
become thinner, as if the ColumnChart determines the bar width
according to the
total number of series, not just the number of column
I thought about trying to add an ItemRenderer to the
ColumnSeries, but it seems that should be an easier way. Any ideas?