Required library edition:

onBeforeCMove event occurs when column moving operation starts;
onAfterCMove event occurs after a column was moved.

These events pass the following parameters:

• cInd - index of the moved column;
• posInd - index of the new position.

        grid.attachEvent("onBeforeCMove", function(cInd,posInd){});
        grid.attachEvent("onAfterCMove", function(cInd,posInd){});