Add Option element and fix Select's Value

Ooui/Node.cs

@@ -74,6 +74,7 @@ namespace Ooui
             }
             newChild.MessageSent += HandleChildMessageSent;
             SendCall ("insertBefore", newChild, referenceChild);
+            OnChildInsertedBefore (newChild, referenceChild);
             return newChild;
         }
 
@@ -88,9 +89,18 @@ namespace Ooui
             }
             child.MessageSent -= HandleChildMessageSent;
             SendCall ("removeChild", child);
+            OnChildRemoved (child);
             return child;
         }
 
+        protected virtual void OnChildInsertedBefore (Node newChild, Node referenceChild)
+        {
+        }
+
+        protected virtual void OnChildRemoved (Node child)
+        {
+        }
+
         protected void ReplaceAll (Node newNode)
         {
             var toRemove = new List<Node> ();

Ooui/Option.cs

@@ -0,0 +1,30 @@
+using System;
+
+namespace Ooui
+{
+    public class Option : Element
+    {
+        string val = "";
+        public string Value {
+            get => val;
+            set => SetProperty (ref val, value ?? "", "value");
+        }
+
+        string label = "";
+        public string Label {
+            get => label;
+            set => SetProperty (ref label, value ?? "", "label");
+        }
+
+        bool defaultSelected = false;
+        public bool DefaultSelected {
+            get => defaultSelected;
+            set => SetProperty (ref defaultSelected, value, "defaultSelected");
+        }
+
+        public Option ()
+            : base ("option")
+        {
+        }
+    }
+}

Ooui/Select.cs

@@ -15,9 +15,37 @@ namespace Ooui
             remove => RemoveEventListener ("change", value);
         }
 
+        public event TargetEventHandler Inputted {
+            add => AddEventListener ("input", value);
+            remove => RemoveEventListener ("input", value);
+        }
+
         public Select ()
             : base ("select")
         {
+            // Subscribe to the change event so we always get up-to-date values
+            Changed += (s, e) => { };
+        }
+
+        public void AddOption (string label, string value)
+        {
+            AppendChild (new Option { Label = label, Value = value });
+        }
+
+        protected override void OnChildInsertedBefore (Node newChild, Node referenceChild)
+        {
+            base.OnChildInsertedBefore (newChild, referenceChild);
+            if (string.IsNullOrEmpty (val) && newChild is Option o && !string.IsNullOrEmpty (o.Value)) {
+                val = o.Value;
+            }
+        }
+
+        protected override bool TriggerEventFromMessage (Message message)
+        {
+            if (message.TargetId == Id && message.MessageType == MessageType.Event && (message.Key == "change" || message.Key == "input")) {
+                val = message.Value != null ? Convert.ToString (message.Value) : "";
+            }
+            return base.TriggerEventFromMessage (message);
         }
     }
 }