So much like a Header is a property of a TreeViewItem, I am trying to add another property that I can reference for my code.

I started looking into DependencyProperty, but I have a feeling this is the wrong direction, as well as making a simple extension to try and set the property I am looking for.

The little snippet that I’m trying to get to work looks a little like this:

public bool AddNewTreeviewChild(ItemCollection selectedTreeView, TreeViewItem selectedItem)
{
    if (selectedTreeView.Contains(selectedItem))
    {
        var newChild = new TreeViewItemExtension();
        newChild.Header = NewItem.Text;
        newChild.TreeViewType = DesignateChildType();
        selectedItem.Items.Add(newChild);
    }

    foreach (TreeViewItem item in selectedTreeView)
    {
        if (AddNewTreeviewChild(item.Items, selectedItem))
        {
            return true;
        }
    }

    return false;
}

The dependency Property way I tried:

public static readonly DependencyProperty TreeViewTypeProp = 
    DependencyProperty.Register(
        "TreeViewType",
        typeof(string),
        typeof(TreeViewItem),
        new PropertyMetadata("Root")
        );

public string TreeViewType
{
    get { return (string)GetValue(TreeViewTypeProp); }
    set { SetValue(TreeViewTypeProp, value); }
}

However, this still makes the TreeViewType inaccessible or unsable in the above example, thus not compiling or running.

I also attempted doing an extension with a simple:

   public class TreeViewItemExtension : TreeViewItem
    {
        public string TreeViewType { get; set; }

        public TreeViewItemExtension ()
        {
            
        }
    }

But when looking at newly added items, the TreeViewType is missing. I tried casting and renaming various TreeViewItems into TreeViewItemExtension, but had no luck. What am I missing?