How and when to use onDragCol in flexigrid jQuery

Question

I am new in using flexigrid.js and I am wondering how and when to use this onDragCol event. I read some code inside of flexigrid.js and it seems that this is an event handler when you finished re sizing the column width.

I tried testing it by setting onDragCol to a function, like onAddCellProp...

onAddCellProp: onAddCellProp,
onDragCol: onDragCol

then I created the function

function onDragCol(columnNumber, columnTable) {
    alert('hi');
}

then I tried resizing the flexigrid column but with no luck wasn't able to fire the onDragCol event. There was no error in firebug regarding javascript and onAddCellProp is normally working and other js implementations.
My question is: How and When can I use onDragCol?