Added Form

Ooui/Form.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace Ooui
+{
+    public class Form : Element
+    {
+        public event EventHandler Submitted {
+            add => AddEventListener ("submit", value);
+            remove => RemoveEventListener ("submit", value);
+        }
+
+        public Form ()
+            : base ("form")
+        {
+        }
+    }
+}

Ooui/FormControl.cs

@@ -16,6 +16,16 @@ namespace Ooui
             set => SetProperty (ref isDisabled, value, "disabled");
         }
 
+        public Form Form {
+            get {
+                var p = ParentNode;
+                while (p != null && !(p is Form)) {
+                    p = p.ParentNode;
+                }
+                return p as Form;
+            }
+        }
+
         public FormControl (string tagName)
             : base (tagName)
         {