Not supported. Determines whether the "first run" page has been shown.
pfShown = window.external.RunOnceHasShown()
Returns one of the following values:
The "first run" page has been shown at least once.
The "first run" page has not been shown.
RunOnceHasShown was introduced in Internet Explorer 7.
This method can only be called from a "first run" page in the correct domain.