This code will open the PDF file using the default reader.
Put the code below into one of the events of the list box, for example, DoubleClick.
ProcessStartInfo infoOpenPdf = new ProcessStartInfo();
infoOpenPdf.Verb = "open";
infoOpenPdf.FileName = pathPdf;
infoOpenPdf.CreateNoWindow = true;
infoOpenPdf.WindowStyle = ProcessWindowStyle.Normal;
Process openPdf = new Process();
openPdf.StartInfo = infoOpenPdf;
openPdf.Start();
Add the following to the top of the source file:
using System.Diagnostics;