CheckIfOfficeIsHTMLEditor Property
True if Microsoft Word checks to see whether an Office application is the default HTML editor when you start Word. False if Word does not perform this check. The default value is True. Read/write Boolean.
Remarks
This property is used only if the Web browser you are using supports HTML editing and HTML editors.
To use a different HTML editor, you must set this property to False and then register the editor as the default system HTML editor.
Example
This example causes Microsoft Word not to check to see whether an Office application is the default HTML editor.
Application.DefaultWebOptions _
.CheckIfOfficeIsHTMLEditor = False