Why do items in TreeViewItem inherit the event handlers of parent?

问题

So, I create a TreeViewItem (parentNode), and I add TreeViewItems into the parentNode TreeViewItem. I then add a MouseButtonEventHandler to the parentNode, and now all the TreeViewItems inside parentNode have the MouseButtonEventHandler. I've run the debugger to see if I have code that was accidentally written to add the MouseButtonHandler, but there isn't...

Edit: I did additional tests, and it even goes two levels down. Is there a way to isolate eventhandlers to only the specific node and not its children and/or parents?

public newClass() {
    TreeViewItem parent = new TreeViewItem();

    TreeViewItem childOne = new TreeviewItem();
    addExpandClickListener(childOne);

    TreeViewItem childTwo = new TreeviewItem();
    TreeViewItem childThree = new TreeViewItem();


    childTwo.Items.Add(childThree);
    childOne.Items.Add(childTwo);
    parent.Items.Add(childOne);
    TreeViewObject.Items.Add(parent);
}

private void addExpandClickListener(TreeViewItem item) { item.MouseLeftButtonUp += new MouseButtonEventHandler(item_MouseClick); }


private void item_MouseClick(object sender, MouseButtonEventArgs e) {
    // Define click event as handled
    e.Handled = true;
    if(sender != e.Source) return;
    // Handle click event
    TreeViewItem root = (TreeViewItem)sender;
    if(root.IsExpanded == true) CollapseRecursive(root);
    else root.IsExpanded = true;
    //else root.ExpandSubtree();
    ViewTree.Items.Refresh();
}

回答1:

The area of the parentNode includes the areas of the children. Think of overlapping rectangles. If you only want to have a click to work for the text part, you'll either have to supply your own DataTemplate or use the visual tree to find the header and apply the click to that.

来源：https://stackoverflow.com/questions/11334651/why-do-items-in-treeviewitem-inherit-the-event-handlers-of-parent