Inserts a new item in the given index.
        
        :param      index | <int>
                    item  | <XGanttWidgetItem>

def insertChild(self, index, item):
        """
        Inserts a new item in the given index.
        
        :param      index | <int>
                    item  | <XGanttWidgetItem>
        """
        super(XGanttWidgetItem, self).insertChild(index, item)
        item.sync()