This event is reported when a user begins to move a dragable datapoint. The message reports the (chart, series, row, column) as a 4-element vector. You may drag markers or bars which are listed in the ‘dragable’ property of the class. Please note that if you drag a bar from a stacked barchart, you will be given the new y-value as the sum of this bar and the bars beneath – it is up to you do subtract the appropriate offset to the base of the bar. You may reject the event by returning 0 from the event-action table (¾„0 or ’Reject) – this could be used to allow selective update from a set of grouped bars.