Note that this value is set during print preparation phase
(GTK_PRINT_STATUS_PREPARING), so this function should never be
called before the data generation phase (GTK_PRINT_STATUS_GENERATING_DATA).
You can connect to the status-changed signal
and call PrintOperation.getNPagesToPrint when
print status is GTK_PRINT_STATUS_GENERATING_DATA.
This is typically used to track the progress of print operation.
Returns the number of pages that will be printed.
Note that this value is set during print preparation phase (GTK_PRINT_STATUS_PREPARING), so this function should never be called before the data generation phase (GTK_PRINT_STATUS_GENERATING_DATA). You can connect to the status-changed signal and call PrintOperation.getNPagesToPrint when print status is GTK_PRINT_STATUS_GENERATING_DATA. This is typically used to track the progress of print operation.