DownloadedType lists the events triggered by calling OpenURLAsync.
public enum DownloadedType
An error has occurred while downloading and downloading has stopped.
The entire document has been downloaded.
The named destinations have been downloaded. These may be necessary for link activation.
The initial document information is available and it is now ok to query for document information.
The document outline (bookmarks) has been downloaded.
A new page has been downloaded.
A thumbnail has been downloaded.