ArcGIS Pro 3.0 API Reference Guide
ArcGIS.Core.CIM Namespace / CIMBackgroundCallout Class / BackgroundSymbol Property

BackgroundSymbol Property (CIMBackgroundCallout)
Gets or sets the symbol used to draw the background. If null, the background doesn't draw.
Syntax
public CIMPolygonSymbol BackgroundSymbol {get; set;}
Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

ArcGIS Pro version: 2.0 or higher.
See Also