Basically I edit an attribute private string status=\"OK\" in the UserObject() of a DefaultTreeNode().
I have a CustomRenderer
When you want the model to be updated, as you do here, you are correct that you want to call nodeChanged. What I think may be wrong is that you are passing in an entirely new node, which obviously doesn't match one found in the tree. Try passing in a reference to the node in the tree you modified - that way the model can find know which node you modified.