ArcGIS Pro 3.0 API Reference Guide
ArcGIS.Desktop.Mapping Namespace / PopupDefinition Class / Position Property

Position Property (PopupDefinition)
Gets or sets the screen coordinates to place the top left corner of the popup window. When set to null, a default position will be used. Only used when dockable is false or the dockable window is floating.
Syntax
public Nullable<Point> Position {get; set;}
Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

ArcGIS Pro version: 2.5 or higher.
See Also