Add my sortdown / sortup icons programmatically in tablesorter header

I want to add my sortDown and sortUp icones dynamically in tablesorter. The problem is, I want to have an image background like green theme in my headers, but the images in 'green' theme don't work for me as when the height of the header is more than one row, the position of开发者_如何学Go the little sorter icons change. the only solution that I come up with is to remove the sorter icon from the background image and add it dynamically in the sortEnd event. But the problem is I don't know how I can find the list of sorted columns in the even and how can I recognize the sort order of each column.

There is an undocumented option named onRenderHeader here is the original demo

But, I've forked a copy of and made a more specific demo here. Also, I've added a jQuery UI theme widget where you can choose your own icons by finding and changing the icon names in the widget.