xls exports hidden columns

melight

I'm trying to export the data set like in the basic initialization setup example. But I'm getting the hidden columns exported also, unlike in the example. I though of using the fnCellRender thing, but it's not a good fit because the indexes of columns I need hidden are dynamic.
Here's my init:

[code]
"oTableTools": {
"sSwfPath": "static/swf/copy_csv_xls.swf",
"aButtons": [
{
"sExtends": "xls",
"sButtonText": "<?=$strings['export']?>"
}
]
},
"sDom": 'T<"clear">lfrtip'
[/code]

Please advise.