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.