code: def setTopLevelItems( self, items ):
          
          self.blockSignals(True)
          
          root = self.invisibleRootItem()
          for row in range(root.rowCount()):
              root.takeRow(row)
          
          for item in items:
              root.appendRow(item)
              
          self.blockSignals(False)
docs: Sets the root item for this model to the inputed item.
          
          :param      item | <XNavigationItem>