Gtk3: Bottom item in a TreeGridView is unable to be expanded

[Prism019]

Expected Behavior

Expanding the bottom item in a TreeGridView will expand when the expansion arrow is clicked, also running the relevant event.

Actual Behavior

The element is not expanded.
The Expanding event of the TreeGridView is not called.

Steps to Reproduce the Problem

1. Click the expand button on the bottom element of a TreeGridView

Code that Demonstrates the Problem

	public partial class MainForm : Form
	{
		// counter for uniquely identifying items in the TreeGridView
		int counter = 0;
		public MainForm()
		{
			// basic stuff
			Title = "Eto Forms TreeGridView Bug";
			MinimumSize = new Size(800, 800);
			
			// create the grid view, add a column to show the text
			var gridView = new TreeGridView();
			Content = gridView;
			gridView.Columns.Add(new GridColumn{HeaderText = "Text", DataCell = new TextBoxCell(0)});

			// create a new item collection, add a CollectionChanged callback to reload the node once added, and add an initial item.
			var gridViewItems = new TreeGridItemCollection();
			gridView.DataStore = gridViewItems;
			gridViewItems.CollectionChanged += (sender, e) => {
				if(e.NewItems == null) {
					return;
				}
			  	foreach(var i in e.NewItems) {
			  		System.Console.WriteLine("Reloading node " + (i as TreeGridItem).Values[0]);
					gridView.ReloadItem(i as TreeGridItem);
				}
			};
			var parentNode = new TreeGridItem{Values = new object[]{"test_parent" + counter}};
			parentNode.Children.Add(new TreeGridItem{Values = new object[]{"test_child" + counter}});
			counter++;
			gridViewItems.Add(parentNode);

			// callback to telegraph when expanding items occurs
			gridView.Expanding += (sender, e) => {
				System.Console.WriteLine("Expanding!");
			};

			// callbacks to manipulate the number of items in the TreeGridView
			gridView.CellClick += (sender, e) => {
				System.Console.WriteLine("Adding!");
				var addedParentNode = new TreeGridItem{Values = new object[]{"test_parent" + counter}};
				addedParentNode.Children.Add(new TreeGridItem{Values = new object[]{"test_child" + counter}});
				counter++;
				gridViewItems.Add(addedParentNode);
			};
			gridView.KeyDown += (sender, e) => {
				System.Console.WriteLine("Removing!");
				gridViewItems.RemoveAt(gridViewItems.Count - 1);
			};
		}
	}

Specifications

• Version: 2.7.1
• Platform(s): Gtk3
• Operating System(s): NixOS 22.05

Additional Comments

I don't have the ability to test other platforms, so I'm not sure what other platforms this affects.