Gtk# Tooltip on NodeView Showing on Incorrect Rows - monodevelop

Question

There appears to be some interesting behavior with the way tooltips are being displayed in Gtk# NodeView instances. Specifically, the GetPathAtPos method is not taking the header row into consideration when returning the TreePath, which in turn causes the tooltip to be displayed under an incorrect row. The following code is being used to demonstrate the issue:
using Gtk;
[TreeNode(ListOnly = true)]
public class MyTreeNode : TreeNode
{
[TreeNodeValue(Column = 0)]
public string RowNumber { get; set; } = "";
[TreeNodeValue(Column = 1)]
public string Data { get; set; } = "";
}
public partial class MainWindow : Gtk.Window
{
public MainWindow() : base(Gtk.WindowType.Toplevel)
{
Build();
nodeview1.AppendColumn("Row Number", new CellRendererText(), "text", 0);
nodeview1.AppendColumn("Data", new CellRendererText(), "text", 1);
NodeStore nodeStore = new NodeStore(typeof(MyTreeNode));
nodeStore.AddNode(new MyTreeNode { RowNumber = "One", Data = "foo" });
nodeStore.AddNode(new MyTreeNode { RowNumber = "Two", Data = "bar" });
nodeStore.AddNode(new MyTreeNode { RowNumber = "Three", Data = "baaz" });
nodeStore.AddNode(new MyTreeNode { RowNumber = "Four", Data = "quux" });
nodeview1.NodeStore = nodeStore;
nodeview1.HasTooltip = true;
nodeview1.QueryTooltip += Nodeview1_QueryTooltip;
}
private void Nodeview1_QueryTooltip(object o, QueryTooltipArgs args)
{
bool result = false;
if (nodeview1.GetPathAtPos(args.X, args.Y, out TreePath path))
{
TreeModel model = nodeview1.Model;
if (model.GetIter(out TreeIter iter, path))
{
string rowNumber = model.GetValue(iter, 0) as string;
args.Tooltip.Text = "This is the tooltip for Row Number " + rowNumber;
result = true;
}
}
args.RetVal = result;
}
protected void OnDeleteEvent(object sender, DeleteEventArgs a)
{
Application.Quit();
a.RetVal = true;
}
}
When hovering the mouse over the row where RowNumber = "Three", the tooltip says, "This is the tooltip for Row Number Four". Similarly, when hovering the mouse over the header, the tooltip says, "This is the tooltip for Row Number One". All of the tooltips behave this way.
As a workaround, I modified the call to GetPathAtPos to pass "args.Y - 23". The header row appears to be 23 pixels high, but of course it is not good practice to hard-code these types of values.
Hopefully someone else has experienced this before and knows how to resolve it or how to work around it more dynamically (for example, knowing how to get the height of the header row at runtime).
The code has been compiled using MonoDevelop 7.8.4 (build 2) on Ubuntu 22.04 LTS. Two things to note:
MonoDevelop supports only GTK 2 (unless anyone knows how to get it to support newer versions).
I am running Ubuntu in a VirtualBox session, with Windows 10 as the host operating system.

Answer 1

After doing some digging that included finding a great visual for Gtk.TreeView, I was able to find a solution. The X and Y values in QueryTooltipArgs are in widget coordinates. They need to be translated to bin window coordinates for GetPathAtPos to work correctly. As a result, the if statement in Nodeview1_QueryTooltip has been modified as follows:
ORIGINAL CODE:
if (nodeview1.GetPathAtPos(args.X, args.Y, out TreePath path))
UPDATED CODE:
nodeview1.ConvertWidgetToBinWindowCoords(args.X, args.Y, out int bx, out int by);
if (nodeview1.GetPathAtPos(bx, by, out TreePath path))