Returns the next item in the tree.
        
        :param      item | <QtGui.QTreeWidgetItem>
        
        :return     <QtGui.QTreeWidgetItem>

def findNextItem(self, item):
        """
        Returns the next item in the tree.
        
        :param      item | <QtGui.QTreeWidgetItem>
        
        :return     <QtGui.QTreeWidgetItem>
        """
        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)