MouseCameraControllerEventsSourceElement Property

public FrameworkElement EventsSourceElement { get; set; }

Property Value

If the property is not set, Viewport3D element on the TargetCamera is used as event source.

Note that if EventsSourceElement property is set to Viewport3D (manually or automatically) the mouse events occur only on the area of Viewport3D that actually shows a content. So mouse events do not happen on the empty area of the Viewport3D. To enable mouse events on the whole area of Viewport3D, add a Grid or Border as a parent of a Viewport3D, set its Background to any Brush - for example White or Transparent and than set the EventsSourceElement or EventsSourceElementName to the added control.

To specify the EventsSourceElement by its name use the EventsSourceElementName property.

Reference