If the browser is displaying content from a local file, this
property returns the full path to that file. Setting this property
will cause the browser to load the local file and display the
contents, similar to specifying a file:// URL to the
Navigate method.
If you assign a value to this property, you can enclose environment
variables in percent (%) symbols and they will automatically be
expanded. For example, you could provide a file path like
"%UserProfile%\Documents" and it would be expanded
to the current user's Documents folder.