code: def addTopLevelItem(self, item):
          
          vitem = item.viewItem()
          
          self.treeWidget().addTopLevelItem(item)
          self.viewWidget().scene().addItem(vitem)
          
          item._viewItem = weakref.ref(vitem)
          
          if self.updatesEnabled():
              try:
                  item.sync(recursive=True)
              except AttributeError:
                  pass
docs: Adds the inputed item to the gantt widget.
          
          :param      item | <XGanttWidgetItem>