const win32ui.PD_PRINTTOFILE;

If this flag is set, the Print to File check box is selected. If this flag is set when the PrintDlg function returns, the offset indicated by the wOutputOffset member of the DEVNAMES structure contains the string "FILE:". When you call theStartDoc function to start the printing operation, specify this "FILE:" string in the lpszOutput member of theDOCINFO structure. Specifying this string causes the print subsystem to query the user for the name of the output file.