_Application.Interactive property

True if Microsoft Excel is in interactive mode; this property is usually True. If you set this property to False, Microsoft Excel will block all input from the keyboard and mouse (except input to dialog boxes that are displayed by your code). Blocking user input will prevent the user from interfering with the code as it moves or activates Microsoft Excel objects.

Namespace:  Microsoft.Office.Interop.Excel
Assembly:  Microsoft.Office.Interop.Excel (in Microsoft.Office.Interop.Excel.dll)

bool Interactive { get; set; }

Property value

Type: System.Boolean

This property is useful if you're writing code to communicate with Microsoft Excel from another application.

If you set this property to False, don't forget to set it back to True. Microsoft Excel won't automatically set this property back to True when your code stops running.