# BuildRoot()

> Implement this method to generate the content of the drop-down. This method is called when the drop-down is being shown.

## Definition

* **Type:** Method
* **Namespace:** [UnityEditor.IMGUI.Controls](/engine/6000.3/script-reference/unityeditor/imgui/controls.md)
* **Assembly:** UnityEditor

```csharp
protected abstract AdvancedDropdownItem BuildRoot()
```

### Returns

| Type                                                                                                       | Description       |
| ---------------------------------------------------------------------------------------------------------- | ----------------- |
| [AdvancedDropdownItem](/engine/6000.3/script-reference/unityeditor/imgui/controls/advanceddropdownitem.md) | Root of the list. |