AssistantPageFunc(currentPage: number, data: object): number
A function used by gtk_assistant_set_forward_page_func() to know which
is the next page given a current one. It's called both for computing the
next page when the user presses the "forward" button and for handling
the behavior of the "last" button.
A function used by gtk_assistant_set_forward_page_func() to know which is the next page given a current one. It's called both for computing the next page when the user presses the "forward" button and for handling the behavior of the "last" button.