Resolved TrackPropertyValue does not invoke callback when property value is changed back to original

So I have been relying on TrackPropertyValue in my code, and I found a part of it (bug?) that is quite annoying. Basically, whenever I do TrackPropertyValue on a property with some oldValue, it doesn't fire my callback when the value of the property changes from some newValue back to oldValue.

For example, in the following code, I have a checkbox that controls a bool serialized property (m_isChecked), and a label that tracks its property value so whenever the checkbox is toggled, it respond to the change by changing its text.

Code (CSharp):

1. public class TestEditorWindow : EditorWindow
2. {
3.     [SerializeField] private bool m_isChecked;
4.     private SerializedObject m_serializedObject;
5.  
6.     [MenuItem("Test/Window")]
7.     private static void OpenTestWindow()
8.     {
9.         GetWindow<TestEditorWindow>();
10.     }
11.  
12.     private void OnEnable()
13.     {
14.         var checkbox = new Toggle("Checkbox");
15.         var label = new Label();
16.         rootVisualElement.Add(checkbox);
17.         rootVisualElement.Add(label);
18.         m_serializedObject = new SerializedObject(this);
19.         var checkedProperty = m_serializedObject.FindProperty(nameof(m_isChecked));
20.         checkbox.BindProperty(checkedProperty);
21.         label.TrackPropertyValue(checkedProperty, _ => label.text = m_isChecked ? "Checked!" : "Not checked!");
22.     }
23.  
24.     private void OnDisable()
25.     {
26.         m_serializedObject?.Dispose();
27.         m_serializedObject = null;
28.     }
29. }

However, the problem is, if the checkbox is initially unchecked, and I then toggle it twice (unchecked => checked => checked), my callback is only executed on the first toggle, not the second one.

I currently use a workaround where I untrack and then re-track the property in the callback:

Code (CSharp):

1. private void OnEnable()
2. {
3.     var checkbox = new Toggle("Checkbox");
4.     var label = new Label();
5.     rootVisualElement.Add(checkbox);
6.     rootVisualElement.Add(label);
7.     m_serializedObject = new SerializedObject(this);
8.     var checkedProperty = m_serializedObject.FindProperty(nameof(m_isChecked));
9.     checkbox.BindProperty(checkedProperty);
10.     label.TrackPropertyValue(checkedProperty, prop => HandleToggled(label, prop));
11. }
12.  
13. private void HandleToggled(Label label, SerializedProperty serializedProperty)
14. {
15.     label.text = m_isChecked ? "Checked!" : "Not checked!";
16.     label.Unbind();
17.     label.TrackPropertyValue(serializedProperty, prop => HandleToggled(label, prop));
18. }

This seems to work. However, it is less than ideal. Is this how we are supposed to use TrackPropertyValue?

Unity version:
2022.1.23f1.git.9844400
Revision: 2022.1/staging 9636b062134a
Built: Mon, 07 Nov 2022 15:38:26 GMT

 

The issue seems to be fixed in 2022.2. The original code works without using the workaround.

----
2022.2.12f1.112.10540
Revision: 2022.2/staging 022dac4955a3
Built: Tue, 14 Mar 2023 09:46:46 GMT