# OverlayIcon

> Gets the VisualElement that represents an icon that overlays over the icon of the item. This element is hidden by default.

## Definition

* **Type:** Property
* **Namespace:** [Unity.Hierarchy](/engine/6000.7/script-reference/unity/hierarchy.md)
* **Assembly:** UnityEngine.HierarchyModule

```csharp
public VisualElement OverlayIcon { get; }
```

### Remarks

Typically used to add an icon that indicates the state of the item. For example, you can use this to display an icon over a GameObject's icon that indicates a prefab has a broken reference.

The following example adds a custom tooltip that displays in the Hierarchy window when you hover over any GameObject that has a custom component named `Notes` attached to it. It uses `OverlayIcon` to add the custom overlay indicator to the icon of the GameObject.

The example requires a USS file called `CustomTooltip.uss` and a custom MonoBehaviour script called `Notes.cs`.

To use this example:

1. Save the script in a folder called `Assets/Editor/CustomTooltip`. Scripts in an `Editor` folder can use the Hierarchy module API without additional setup. If you save the script outside of an `Editor` folder, you must enable the Hierarchy built-in module in the **Package Manager** window, which also adds the module to your Player builds.
2. Copy the styles from the USS example on this page. Save them in a USS file called `CustomTooltip.uss` in the same `Assets/Editor/CustomTooltip` folder.
3. Save the `Notes.cs` script outside of an `Editor` folder, because MonoBehaviour scripts in an `Editor` folder can't be attached to GameObjects.
4. Add the `Notes` component to a GameObject.
5. In the **Inspector** window, enter text in the **Note** field of the `Notes` component.
6. In the Hierarchy window, hover over the name of the GameObject to display the text as a tooltip. A small overlay indicator also displays in the corner of the icon of any GameObject that has a note.

```csharp
using System.Text;
using Unity.Hierarchy;
using Unity.Hierarchy.Editor;
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;

namespace Unity.HierarchySamples.Editor
{
 class CustomTooltip
 {
 const string k_NotesOverlayUssClassName = "hierarchy-item__notes-overlay";

 [InitializeOnLoadMethod]
 static void Initialize()
 {
 HierarchyWindow.BindView += OnBindView;
 HierarchyWindow.BindViewItem += OnBindViewItem;
 HierarchyWindow.GetTooltip += OnGetTooltip;
 }

 static void OnBindView(HierarchyWindow window, HierarchyView view)
 => view.styleSheets.Add(AssetDatabase.LoadAssetAtPath<StyleSheet>("Assets/Editor/CustomTooltip/CustomTooltip.uss"));

 static void OnBindViewItem(HierarchyWindow window, HierarchyView view, HierarchyViewItem item)
 {
 if (item.Handler is not HierarchyGameObjectHandler handler)
 return;

 GameObject gameObject = handler.GetGameObject(item.Node);

 bool hasNotes = gameObject.TryGetComponent<Notes>(out Notes notes) && !string.IsNullOrWhiteSpace(notes.note);

 VisualElement notesOverlay = item.OverlayIcon.Q(className: k_NotesOverlayUssClassName);

 if (hasNotes)
 {
 if (notesOverlay == null)
 {
 notesOverlay = new VisualElement();
 notesOverlay.AddToClassList(k_NotesOverlayUssClassName);
 item.OverlayIcon.Add(notesOverlay);
 }
 }
 else if (notesOverlay != null)
 {
 notesOverlay.RemoveFromHierarchy();
 }
 }

 static void OnGetTooltip(HierarchyWindow window, HierarchyView view, HierarchyViewItem item, StringBuilder tooltip, bool filtering)
 {
 if (item.Handler is not HierarchyGameObjectHandler handler)
 return;

 GameObject gameObject = handler.GetGameObject(item.Node);

 if (!gameObject.TryGetComponent<Notes>(out Notes notes) || string.IsNullOrWhiteSpace(notes.note))
 return;

 if (filtering)
 {
 // When filtering, append the note to the existing tooltip.
 tooltip.Append("\nNote: ");
 tooltip.Append(notes.note);
 }
 else
 {
 // When not filtering, fully override the tooltip.
 tooltip.Clear();
 tooltip.Append("Note: ");
 tooltip.Append(notes.note);
 }
 }
 }
}
```

The following example shows how to style `CustomTooltip.uss`.

```csharp
.hierarchy-item__notes-overlay {
 position: absolute;
 width: 100%;
 height: 100%;
 background-size: 8px 8px;
 background-position: top left;
 background-repeat: no-repeat;
 background-image: var(--unity-icons-console_entry_info_small);
}
```

The following example shows the `Notes` component that the CustomTooltip example uses.

```csharp
using UnityEngine;

namespace Unity.HierarchySamples
{
 // Simple component that allows attaching notes to GameObjects for display in custom tooltips.
 public class Notes : MonoBehaviour
 {
 [TextArea(3, 10)]
 public string note;
 }
}
```