Restrict possible driver values

OpenEphys.Onix1/ContextDriverConverter.cs

@@ -0,0 +1,25 @@
+using System.ComponentModel;
+
+namespace OpenEphys.Onix1
+{
+    internal class ContextDriverConverter : StringConverter
+    {
+        public override bool GetStandardValuesSupported(ITypeDescriptorContext context)
+        {
+            return true;
+        }
+
+        public override bool GetStandardValuesExclusive(ITypeDescriptorContext context)
+        {
+            return true;
+        }
+
+        public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context)
+        {
+            return new StandardValuesCollection(new[]
+            {
+                "riffa"
+            });
+        }
+    }
+}

OpenEphys.Onix1/CreateContext.cs

@@ -19,6 +19,7 @@ public class CreateContext
         /// </summary>
         [Description("Specifies the device driver used to communicate with hardware.")]
         [Category(DeviceFactory.ConfigurationCategory)]
+        [TypeConverter(typeof(ContextDriverConverter))]
         public string Driver { get; set; } = ContextTask.DefaultDriver;
 
         /// <summary>