ArcGIS Pro 2.7 API Reference Guide
MessageBox Class
Members 

ArcGIS.Desktop.Framework.Dialogs Namespace : MessageBox Class
Represents a dialog box for simple messages.
Syntax
public class MessageBox 
Public Class MessageBox 
Inheritance Hierarchy

System.Object
   ArcGIS.Desktop.Framework.Dialogs.MessageBox

Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

MessageBox Members
ArcGIS.Desktop.Framework.Dialogs Namespace