TreeView custom components and intercepting mouse clicks

If a TreeVIewItem returns a custom component that intercepts mouse clicks how should I handle selections (presumably from the mouseDown callback in the custom component) if the tree is in multiselect mode?

Hello! Is this super hard?

Let me explain what I’m trying to do in case there’s another way:

When a user moves the mouse over a row in a tree view I’d like a button to make itself visible on that row.