string val = FormResults.InputBox(this, TXTDataFolder.Text, "HL7 Data Folder",

            "Enter the full path to the HL7 Data Folder below").Trim();

if (FormResults.FormCancelled) { return; }

  if (!string.IsNullOrEmpty(val))

   {

       //Code

       //Code

       //Code

   }

See Also: the FormCancelled property.