a set of flags denoting what has changed. Possible values:
0x0001
The current page has switched to a different number,
e.g., from page number 3 to page 4.0x0002
The page count (number of pages) has changed.0x0004
The current module has changed (switched to a different module).0x0008
The current module was cleared.For details (and further flags), please consult the documentation of the Nlview API.
the current page number
the total number of pages
Handler for changes to the current page.