# Sandbox.UI.BaseTreeView.ExpandOnDoubleClick

```csharp
bool ExpandOnDoubleClick { get; set; }
```

Double-clicking a closed branch opens it before activation. Open branches stay open.
Disable this when the activation handler manages expansion itself.

Declared in [Sandbox.UI.BaseTreeView](/api/Sandbox.UI.BaseTreeView).
Assembly: `Sandbox.Engine`.