Updates the item information from the tree.
        
        :param      item    | <XGanttWidgetItem>
                    index   | <int>

def updateItemData(self, item, index):
        """
        Updates the item information from the tree.
        
        :param      item    | <XGanttWidgetItem>
                    index   | <int>
        """
        from projexui.widgets.xganttwidget.xganttwidgetitem import XGanttWidgetItem
        if not isinstance(item, XGanttWidgetItem):
            return
        
        value = unwrapVariant(item.data(index, Qt.EditRole))
        
        if type(value) == QDateTime:
            value = value.date()
            item.setData(index, Qt.EditRole, wrapVariant(value))
        
        if type(value) == QDate:
            value = value.toPython()
        
        columnName = self.treeWidget().columnOf(index)
        item.setProperty(columnName, value)
        item.sync()