TreeView usage

[jeffjl]

I'm trying to make a new window for harvesting data. I thought a setup like the quest journal would be a way to organize it. The journal uses a TreeView widget. But I can't figure out how to handle a tree selection. I want to show the harvest details for the selected tree item. Neither the TreeView nor the DataSourceContainer have the OnPress action. So can I not do it this way? Tree selection is not a function of the UI?

I've attached a screenshot of my starting attempt at the tree.