code: def findNextItem(self, item):
          
          if not item:
              return None
          
          if item.childCount():
              return item.child(0)
          
          while item.parent():
              index = item.parent().indexOfChild(item)
              child = item.parent().child(index+1)
              if child:
                  return child
              
              item = item.parent()
          
          index = self.indexOfTopLevelItem(item)
          return self.topLevelItem(index+1)
docs: Returns the next item in the tree.
          
          :param      item | <QtGui.QTreeWidgetItem>
          
          :return     <QtGui.QTreeWidgetItem>