>Is there anyone how can help me to understand how you can catch which node is expanded when a treeview control is expanded?

Could you share your reasons for this requirement. We might be able to help you better if you can. Like "What are you trying to do?"

Remember to add a line in your code in the the node click event to explicitly assure the node select the node:
this.node.selected=.t. && (I think it goes like that!)

Terry