Opening a “known file type” into running instance of custom app - .NET

// This should all be refactored to make it less tightly-coupled, obviously.
class MyWindowsApplicationBase : WindowsFormsApplicationBase
{
  internal MyWindowsApplicationBase() : base()
  {
    // This is a single instance application.
    this.IsSingleInstance = true;

    // Set to the instance of your form to run.
    this.MainForm = new MyForm();
  }
}

// This should all be refactored to make it less tightly-coupled, obviously.
public static void Main(string args[])
{
  // Process the args.
  <process args here>

  // Create the application base.
  MyWindowsApplicationBase appBase = new MyWindowsApplicationBase();

  // <1> Set the StartupNextInstance event handler.
  appBase.StartupNextInstance = <event handler code>;

  // Show the main form of the app.
  appBase.Run(args);
}