ArcGIS Pro 2.7 API Reference Guide
TOCDragData Interface
Members 

ArcGIS.Desktop.Mapping Namespace : TOCDragData Interface
Provides access to map member content dragged off the TOC
Syntax
public interface TOCDragData 
Public Interface TOCDragData 
Remarks
The public API only supports retrieving drag data for the TOC within the same Pro process. Check InProcess to determine if the drag was initiated within the same Pro process or not.
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

TOCDragData Members
ArcGIS.Desktop.Mapping Namespace