# Sandbox.UI.Panel.OnMouseWheel

```csharp
void OnMouseWheel(Vector2 value)
```

Called when the player scrolls their mouse wheel while hovering this panel.

### Parameters

- `value` (`Vector2`): The scroll wheel delta. Positive values are scrolling down, negative - up.

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