Thanks for pointing this out!

Thank you for implementing this. Very cool.

But it does... See http://jsfiddle.net/highcharts/S6435/

Yes. This would be bvery useful for comparing with a 'target' series.
It should work in combination with normat stacking.
See this mockup: http://minus.com/i/OrqLzob3rP6f

I would like to influence the relative width of the columns

Have you considered setting grouping to false? http://api.highcharts.com/highcharts#plotOptions.column.grouping

i'm looking for this feature too. Be able to overlaid 2 series together. Something like this:

plotOptions: {
column: {
stacking: 'overlaid'
}
},

series: [
// first stack
{
data: [29.9, 71.5, 106.4, 129.2, 144.0],
stack: 0
}
// second stack
{
data: [106.4, 129.2, 144.0, 29.9, 71.5],
stack: 1
}, {
data: [148.5, 216.4, 30, 176.0, 135.6],
stack: 1
}]

Thinking about it more, it would be nice to have the ability to control the start date and end date of a column -- so you can control how fat each bar is using a time based x-axis.

But for a series of say 3 different values as in the LayeredBarRenderer(), we could create some sort of scalar so the extra columns in the same series would be relative to the first column.

xAxis: { type: 'datetime' },
plotOptions: {
column: {
scale: {1.0, 0.8, 0.6} //important to control these independently rather than linearly with a single value
}
},

series: [{
name: 'Consumption1',
data: [
[Date.UTC(2012, 0, 1), 100, Date.UTC(2012, 0, 1) ],
[Date.UTC(2012, 1, 1), 143, Date.UTC(2012, 1, 29) ],
[Date.UTC(2012, 2, 1), 122, Date.UTC(2012, 2, 31) ], ...

name: 'Consumption2',
data: [
[Date.UTC(2012, 0, 1), 200, Date.UTC(2012, 0, 1) ],
[Date.UTC(2012, 1, 1), 243, Date.UTC(2012, 1, 29) ],
[Date.UTC(2012, 2, 1), 222, Date.UTC(2012, 2, 31) ], ...

name: 'Consumption3',
data: [
[Date.UTC(2012, 0, 1), 300, Date.UTC(2012, 0, 1) ],
[Date.UTC(2012, 1, 1), 343, Date.UTC(2012, 1, 29) ],
[Date.UTC(2012, 2, 1), 322, Date.UTC(2012, 2, 31) ], ...
}]

Something equivalent to JFreeChart's LayeredBarRenderer()?

http://www.java2s.com/Code/Java/Chart/JFreeChartLayeredBarChartDemo2asuperimposedverticalbarchart.htm

Overlaying charts is something I'd really like to see as well.

Thank you Torstein, that looks rather nice. It's not the effect I'm after though. Also, like you say, it's bit of trickery. If the number of series changes, than also the groupPadding value has to be adjusted.

At this moment I'm thinking of tinkering with the source code. Maybe you give me some advice?

At line 11119 I added "&& stacking!=='overlay'".

// calculate the bottom y value for stacked series
if (stacking && series.visible && stack && stack[xValue] && stacking!=='overlay') {

Now if I choose 'overlay' as the stacking mode, the colums are rendered on top of each other, which is the effect I'm after. It would be even nicer if, optionally, the overlayed columns can get gradationally narrower (bottom one is the widest, subsequent columns are narrower).

Cheers,
Almar

Yes please! I'm really missing this feature. I would like to show scores against targets -- showing two columns in a group doesn't give us the 'right' look.