how can I open it in a certain PDF viewer programmatically from inside my application?
We have added an option since version 2.04 to run an application once the printing is completed. So if you add the value PostProcessing to FileNameOptions, the application that is defined in the registry under HKEY_CURRENT_CONFIG\Software\PrinterName,
key name: PostProcessing, is executed.
The same is done when you check the 'Preview PDF file' check box in the configuration tab. When you do this you are actually setting the PostProcessing flag and changing the registry to point to whatever PDF reader the user selects. This means that you cannot have the Preview PDF file and PostProcessing both running, as they are the same.