ArcGIS Pro 2.6 API Reference Guide
ViewSizeChanged Event

ArcGIS.Desktop.Mapping Namespace > MapView Class : ViewSizeChanged Event
Occurs when the view size changed. Use GetViewSize to get the size.
Syntax
public event EventHandler ViewSizeChanged
Public Event ViewSizeChanged As EventHandler
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

MapView Class
MapView Members