Mine

		private void OnMotionNotifyEvent (object sender, Gtk.MotionNotifyEventArgs args) 
		{
			Console.WriteLine("here");
			
			TreePath path;
			TreeIter iter;
			
			TreeView tv = (TreeView) sender;
			
			tv.GetPathAtPos((int) args.Event.X, (int) args.Event.Y, out path);
			
			buddy_tree.Model.GetIter (out iter, path);		
			Buddy info = (Buddy ) buddy_tree.Model.GetValue (iter, COL_BUDDY);
			
			ContactCardPopup popup = new ContactCardPopup ();
			popup.DisplayLabel = info.Name;
			popup.StatusLabel = "Available";
			popup.Avatar = info.VCard.Photo;
			popup.Show ();	
		}