diff --git a/servo/components/script/dom/activation.rs b/servo/components/script/dom/activation.rs
new file mode 100644
index 000000000000..e4a54112e585
--- /dev/null
+++ b/servo/components/script/dom/activation.rs
@@ -0,0 +1,65 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::EventBinding::EventMethods;
+use dom::bindings::codegen::InheritTypes::{EventCast, EventTargetCast};
+use dom::bindings::js::{JSRef, Temporary, OptionalRootable};
+use dom::element::{Element, ActivationElementHelpers};
+use dom::event::{Event, EventHelpers};
+use dom::eventtarget::{EventTarget, EventTargetHelpers};
+use dom::mouseevent::MouseEvent;
+use dom::node::window_from_node;
+
+
+/// Trait for elements with defined activation behavior
+pub trait Activatable : Copy {
+    fn as_element(&self) -> Temporary<Element>;
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#run-pre-click-activation-steps
+    fn pre_click_activation(&self);
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#run-canceled-activation-steps
+    fn canceled_activation(&self);
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#run-post-click-activation-steps
+    fn activation_behavior(&self);
+
+    // https://html.spec.whatwg.org/multipage/forms.html#implicit-submission
+    fn implicit_submission(&self, ctrlKey: bool, shiftKey: bool, altKey: bool, metaKey: bool);
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#run-synthetic-click-activation-steps
+    fn synthetic_click_activation(&self, ctrlKey: bool, shiftKey: bool, altKey: bool, metaKey: bool) {
+        let element = self.as_element().root();
+        // Step 1
+        if element.click_in_progress() {
+            return;
+        }
+        // Step 2
+        element.set_click_in_progress(true);
+        // Step 3
+        self.pre_click_activation();
+
+        // Step 4
+        // https://html.spec.whatwg.org/multipage/webappapis.html#fire-a-synthetic-mouse-event
+        let win = window_from_node(*element).root();
+        let target: JSRef<EventTarget> = EventTargetCast::from_ref(*element);
+        let mouse = MouseEvent::new(*win, "click".to_string(), false, false, Some(*win), 1,
+                                    0, 0, 0, 0, ctrlKey, shiftKey, altKey, metaKey,
+                                    0, None).root();
+        let event: JSRef<Event> = EventCast::from_ref(*mouse);
+        event.set_trusted(true);
+        target.dispatch_event_with_target(None, event).ok();
+
+        // Step 5
+        if event.DefaultPrevented() {
+            self.canceled_activation();
+        } else {
+            // post click activation
+            self.activation_behavior();
+        }
+
+        // Step 6
+        element.set_click_in_progress(false);
+    }
+}
diff --git a/servo/components/script/dom/bindings/js.rs b/servo/components/script/dom/bindings/js.rs
index f24115a349a9..c9f3e157b75c 100644
--- a/servo/components/script/dom/bindings/js.rs
+++ b/servo/components/script/dom/bindings/js.rs
@@ -575,3 +575,24 @@ impl<'a, T: Reflectable> Reflectable for JSRef<'a, T> {
         self.deref().reflector()
     }
 }
+
+/// A trait for comparing smart pointers ignoring the lifetimes
+pub trait Comparable<T> {
+    fn equals(&self, other: T) -> bool;
+}
+
+impl<'a, 'b, T> Comparable<JSRef<'a, T>> for JSRef<'b, T> {
+    fn equals(&self, other: JSRef<'a, T>) -> bool {
+        self.ptr == other.ptr
+    }
+}
+
+impl<'a, 'b, T> Comparable<Option<JSRef<'a, T>>> for Option<JSRef<'b, T>> {
+    fn equals(&self, other: Option<JSRef<'a, T>>) -> bool {
+        match (*self, other) {
+            (Some(x), Some(y)) => x.ptr == y.ptr,
+            (None, None) => true,
+            _ => false
+        }
+    }
+}
diff --git a/servo/components/script/dom/document.rs b/servo/components/script/dom/document.rs
index f282aa3b483c..fad44638f646 100644
--- a/servo/components/script/dom/document.rs
+++ b/servo/components/script/dom/document.rs
@@ -966,7 +966,6 @@ impl<'a> DocumentMethods for JSRef<'a, Document> {
         self.ready_state.get()
     }
 
-    event_handler!(click, GetOnclick, SetOnclick)
-    event_handler!(load, GetOnload, SetOnload)
+    global_event_handlers!()
     event_handler!(readystatechange, GetOnreadystatechange, SetOnreadystatechange)
 }
diff --git a/servo/components/script/dom/element.rs b/servo/components/script/dom/element.rs
index 36ce1102eb59..ec06678e50c6 100644
--- a/servo/components/script/dom/element.rs
+++ b/servo/components/script/dom/element.rs
@@ -4,6 +4,7 @@
 
 //! Element nodes.
 
+use dom::activation::Activatable;
 use dom::attr::{Attr, ReplacedAttr, FirstSetAttr, AttrHelpers, AttrHelpersForLayout};
 use dom::attr::{AttrValue, StringAttrValue, UIntAttrValue, AtomAttrValue};
 use dom::namednodemap::NamedNodeMap;
@@ -11,9 +12,10 @@ use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::AttrBinding::AttrMethods;
 use dom::bindings::codegen::Bindings::ElementBinding;
 use dom::bindings::codegen::Bindings::ElementBinding::ElementMethods;
+use dom::bindings::codegen::Bindings::EventBinding::EventMethods;
 use dom::bindings::codegen::Bindings::NamedNodeMapBinding::NamedNodeMapMethods;
-use dom::bindings::codegen::InheritTypes::{ElementDerived, HTMLInputElementDerived};
-use dom::bindings::codegen::InheritTypes::{HTMLTableCellElementDerived, NodeCast};
+use dom::bindings::codegen::InheritTypes::{ElementDerived, HTMLInputElementDerived, HTMLTableCellElementDerived};
+use dom::bindings::codegen::InheritTypes::{HTMLInputElementCast, NodeCast, EventTargetCast, ElementCast};
 use dom::bindings::js::{MutNullableJS, JS, JSRef, Temporary, TemporaryPushable};
 use dom::bindings::js::{OptionalSettable, OptionalRootable, Root};
 use dom::bindings::utils::{Reflectable, Reflector};
@@ -24,12 +26,13 @@ use dom::domrect::DOMRect;
 use dom::domrectlist::DOMRectList;
 use dom::document::{Document, DocumentHelpers, LayoutDocumentHelpers};
 use dom::domtokenlist::DOMTokenList;
-use dom::eventtarget::{EventTarget, NodeTargetTypeId};
+use dom::event::Event;
+use dom::eventtarget::{EventTarget, NodeTargetTypeId, EventTargetHelpers};
 use dom::htmlcollection::HTMLCollection;
 use dom::htmlinputelement::{HTMLInputElement, RawLayoutHTMLInputElementHelpers};
 use dom::htmlserializer::serialize;
 use dom::htmltablecellelement::{HTMLTableCellElement, HTMLTableCellElementHelpers};
-use dom::node::{ElementNodeTypeId, Node, NodeHelpers, NodeIterator, document_from_node};
+use dom::node::{ElementNodeTypeId, Node, NodeHelpers, NodeIterator, document_from_node, CLICK_IN_PROGRESS};
 use dom::node::{window_from_node, LayoutNodeHelpers};
 use dom::nodelist::NodeList;
 use dom::virtualmethods::{VirtualMethods, vtable_for};
@@ -1184,3 +1187,92 @@ impl<'a> style::TElement<'a> for JSRef<'a, Element> {
         }
     }
 }
+
+pub trait ActivationElementHelpers<'a> {
+    fn as_maybe_activatable(&'a self) -> Option<&'a Activatable + 'a>;
+    fn click_in_progress(self) -> bool;
+    fn set_click_in_progress(self, click: bool);
+    fn nearest_activable_element(self) -> Option<Temporary<Element>>;
+    fn authentic_click_activation<'b>(self, event: JSRef<'b, Event>);
+}
+
+impl<'a> ActivationElementHelpers<'a> for JSRef<'a, Element> {
+    fn as_maybe_activatable(&'a self) -> Option<&'a Activatable + 'a> {
+        let node: JSRef<Node> = NodeCast::from_ref(*self);
+        match node.type_id() {
+            ElementNodeTypeId(HTMLInputElementTypeId) => {
+                let element: &'a JSRef<'a, HTMLInputElement> = HTMLInputElementCast::to_borrowed_ref(self).unwrap();
+                Some(element as &'a Activatable + 'a)
+            },
+            _ => {
+                None
+            }
+        }
+    }
+
+    fn click_in_progress(self) -> bool {
+        let node: JSRef<Node> = NodeCast::from_ref(self);
+        node.get_flag(CLICK_IN_PROGRESS)
+    }
+
+    fn set_click_in_progress(self, click: bool) {
+        let node: JSRef<Node> = NodeCast::from_ref(self);
+        node.set_flag(CLICK_IN_PROGRESS, click)
+    }
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#nearest-activatable-element
+    fn nearest_activable_element(self) -> Option<Temporary<Element>> {
+        match self.as_maybe_activatable() {
+            Some(el) => Some(Temporary::from_rooted(*el.as_element().root())),
+            None => {
+                let node: JSRef<Node> = NodeCast::from_ref(self);
+                node.ancestors()
+                    .filter_map(|node| ElementCast::to_ref(node))
+                    .filter(|e| e.as_maybe_activatable().is_some()).next()
+                    .map(|r| Temporary::from_rooted(r))
+            }
+        }
+    }
+
+    /// Please call this method *only* for real click events
+    ///
+    /// https://html.spec.whatwg.org/multipage/interaction.html#run-authentic-click-activation-steps
+    ///
+    /// Use an element's synthetic click activation (or handle_event) for any script-triggered clicks.
+    /// If the spec says otherwise, check with Manishearth first
+    fn authentic_click_activation<'b>(self, event: JSRef<'b, Event>) {
+        // Not explicitly part of the spec, however this helps enforce the invariants
+        // required to save state between pre-activation and post-activation
+        // since we cannot nest authentic clicks (unlike synthetic click activation, where
+        // the script can generate more click events from the handler)
+        assert!(!self.click_in_progress());
+
+        let target: JSRef<EventTarget> = EventTargetCast::from_ref(self);
+        // Step 2 (requires canvas support)
+        // Step 3
+        self.set_click_in_progress(true);
+        // Step 4
+        let e = self.nearest_activable_element().root();
+        match e {
+            Some(el) => match el.as_maybe_activatable() {
+                Some(elem) => {
+                    // Step 5-6
+                    elem.pre_click_activation();
+                    target.dispatch_event_with_target(None, event).ok();
+                    if !event.DefaultPrevented() {
+                        // post click activation
+                        elem.activation_behavior();
+                    } else {
+                        elem.canceled_activation();
+                    }
+                }
+                // Step 6
+                None => {target.dispatch_event_with_target(None, event).ok();}
+            },
+            // Step 6
+            None => {target.dispatch_event_with_target(None, event).ok();}
+        }
+        // Step 7
+        self.set_click_in_progress(false);
+    }
+}
diff --git a/servo/components/script/dom/event.rs b/servo/components/script/dom/event.rs
index 637bd259035d..6d7ce64bf5e6 100644
--- a/servo/components/script/dom/event.rs
+++ b/servo/components/script/dom/event.rs
@@ -245,3 +245,13 @@ impl Reflectable for Event {
         &self.reflector_
     }
 }
+
+pub trait EventHelpers {
+    fn set_trusted(self, trusted: bool);
+}
+
+impl<'a> EventHelpers for JSRef<'a, Event> {
+    fn set_trusted(self, trusted: bool) {
+        self.trusted.set(trusted);
+    }
+}
diff --git a/servo/components/script/dom/htmlelement.rs b/servo/components/script/dom/htmlelement.rs
index 75ad910ee2eb..010946fabc4d 100644
--- a/servo/components/script/dom/htmlelement.rs
+++ b/servo/components/script/dom/htmlelement.rs
@@ -7,14 +7,15 @@ use dom::attr::AttrHelpers;
 use dom::bindings::codegen::Bindings::EventHandlerBinding::EventHandlerNonNull;
 use dom::bindings::codegen::Bindings::HTMLElementBinding;
 use dom::bindings::codegen::Bindings::HTMLElementBinding::HTMLElementMethods;
+use dom::bindings::codegen::Bindings::HTMLInputElementBinding::HTMLInputElementMethods;
 use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
 use dom::bindings::codegen::InheritTypes::{ElementCast, HTMLFrameSetElementDerived};
-use dom::bindings::codegen::InheritTypes::EventTargetCast;
+use dom::bindings::codegen::InheritTypes::{EventTargetCast, HTMLInputElementCast};
 use dom::bindings::codegen::InheritTypes::{HTMLElementDerived, HTMLBodyElementDerived};
 use dom::bindings::js::{JSRef, Temporary};
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::document::Document;
-use dom::element::{Element, ElementTypeId, ElementTypeId_, HTMLElementTypeId};
+use dom::element::{Element, ElementTypeId, ElementTypeId_, HTMLElementTypeId, ActivationElementHelpers};
 use dom::eventtarget::{EventTarget, EventTargetHelpers, NodeTargetTypeId};
 use dom::node::{Node, ElementNodeTypeId, window_from_node};
 use dom::virtualmethods::VirtualMethods;
@@ -74,7 +75,7 @@ impl<'a> HTMLElementMethods for JSRef<'a, HTMLElement> {
     make_bool_getter!(Hidden)
     make_bool_setter!(SetHidden, "hidden")
 
-    event_handler!(click, GetOnclick, SetOnclick)
+    global_event_handlers!(NoOnload)
 
     fn GetOnload(self) -> Option<EventHandlerNonNull> {
         if self.is_body_or_frameset() {
@@ -91,6 +92,18 @@ impl<'a> HTMLElementMethods for JSRef<'a, HTMLElement> {
             win.SetOnload(listener)
         }
     }
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#dom-click
+    fn Click(self) {
+        let maybe_input = HTMLInputElementCast::to_ref(self);
+        match maybe_input {
+            Some(i) if i.Disabled() => return,
+            _ => ()
+        }
+        let element: JSRef<Element> = ElementCast::from_ref(self);
+        // https://www.w3.org/Bugs/Public/show_bug.cgi?id=27430 ?
+        element.as_maybe_activatable().map(|a| a.synthetic_click_activation(false, false, false, false));
+    }
 }
 
 impl<'a> VirtualMethods for JSRef<'a, HTMLElement> {
diff --git a/servo/components/script/dom/htmlformelement.rs b/servo/components/script/dom/htmlformelement.rs
index a8461618db95..1d12bdebf39b 100644
--- a/servo/components/script/dom/htmlformelement.rs
+++ b/servo/components/script/dom/htmlformelement.rs
@@ -15,7 +15,7 @@ use dom::bindings::utils::{Reflectable, Reflector};
 use dom::document::{Document, DocumentHelpers};
 use dom::element::{Element, AttributeHandlers, HTMLFormElementTypeId, HTMLTextAreaElementTypeId, HTMLDataListElementTypeId};
 use dom::element::{HTMLInputElementTypeId, HTMLButtonElementTypeId, HTMLObjectElementTypeId, HTMLSelectElementTypeId};
-use dom::event::{Event, Bubbles, Cancelable};
+use dom::event::{Event, EventHelpers, Bubbles, Cancelable};
 use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
 use dom::htmlinputelement::HTMLInputElement;
@@ -142,6 +142,7 @@ impl<'a> HTMLFormElementHelpers for JSRef<'a, HTMLFormElement> {
         let event = Event::new(Window(*win),
                                "submit".to_string(),
                                Bubbles, Cancelable).root();
+        event.set_trusted(true);
         let target: JSRef<EventTarget> = EventTargetCast::from_ref(self);
         target.DispatchEvent(*event).ok();
         if event.DefaultPrevented() {
@@ -410,7 +411,7 @@ impl<'a> FormSubmitter<'a> {
     }
 }
 
-pub trait FormOwner<'a> : Copy {
+pub trait FormControl<'a> : Copy {
     fn form_owner(self) -> Option<Temporary<HTMLFormElement>>;
     fn get_form_attribute(self,
                           attr: &Atom,
@@ -423,4 +424,6 @@ pub trait FormOwner<'a> : Copy {
         }
     }
     fn to_element(self) -> JSRef<'a, Element>;
+    // https://html.spec.whatwg.org/multipage/forms.html#concept-fe-mutable
+    fn mutable(self) -> bool;
 }
diff --git a/servo/components/script/dom/htmlinputelement.rs b/servo/components/script/dom/htmlinputelement.rs
index 20227cd397ee..a736a7a8f3da 100644
--- a/servo/components/script/dom/htmlinputelement.rs
+++ b/servo/components/script/dom/htmlinputelement.rs
@@ -2,28 +2,31 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use dom::activation::Activatable;
 use dom::attr::{Attr, AttrValue, UIntAttrValue};
 use dom::attr::AttrHelpers;
 use dom::bindings::cell::DOMRefCell;
 use dom::bindings::codegen::Bindings::AttrBinding::AttrMethods;
 use dom::bindings::codegen::Bindings::DocumentBinding::DocumentMethods;
 use dom::bindings::codegen::Bindings::EventBinding::EventMethods;
+use dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetMethods;
 use dom::bindings::codegen::Bindings::HTMLInputElementBinding;
 use dom::bindings::codegen::Bindings::HTMLInputElementBinding::HTMLInputElementMethods;
-use dom::bindings::codegen::Bindings::NodeListBinding::NodeListMethods;
 use dom::bindings::codegen::InheritTypes::{ElementCast, HTMLElementCast, HTMLFormElementCast, HTMLInputElementCast, NodeCast};
-use dom::bindings::codegen::InheritTypes::{HTMLInputElementDerived, HTMLFieldSetElementDerived};
+use dom::bindings::codegen::InheritTypes::{HTMLInputElementDerived, HTMLFieldSetElementDerived, EventTargetCast};
 use dom::bindings::codegen::InheritTypes::KeyboardEventCast;
-use dom::bindings::js::{JS, JSRef, Temporary, OptionalRootable, ResultRootable};
+use dom::bindings::global::Window;
+use dom::bindings::js::{Comparable, JS, JSRef, Root, Temporary, OptionalRootable};
+use dom::bindings::js::{ResultRootable, RootedReference, MutNullableJS};
 use dom::bindings::utils::{Reflectable, Reflector};
 use dom::document::{Document, DocumentHelpers};
 use dom::element::{AttributeHandlers, Element, HTMLInputElementTypeId};
-use dom::element::RawLayoutElementHelpers;
-use dom::event::Event;
+use dom::element::{RawLayoutElementHelpers, ActivationElementHelpers};
+use dom::event::{Event, Bubbles, NotCancelable, EventHelpers};
 use dom::eventtarget::{EventTarget, NodeTargetTypeId};
 use dom::htmlelement::HTMLElement;
 use dom::keyboardevent::KeyboardEvent;
-use dom::htmlformelement::{InputElement, FormOwner, HTMLFormElement, HTMLFormElementHelpers, NotFromFormSubmitMethod};
+use dom::htmlformelement::{InputElement, FormControl, HTMLFormElement, HTMLFormElementHelpers, NotFromFormSubmitMethod};
 use dom::node::{DisabledStateHelpers, Node, NodeHelpers, ElementNodeTypeId, document_from_node, window_from_node};
 use dom::virtualmethods::VirtualMethods;
 use textinput::{Single, TextInput, TriggerDefaultAction, DispatchInput, Nothing};
@@ -33,6 +36,7 @@ use string_cache::Atom;
 
 use std::ascii::OwnedAsciiExt;
 use std::cell::Cell;
+use std::default::Default;
 
 const DEFAULT_SUBMIT_VALUE: &'static str = "Submit";
 const DEFAULT_RESET_VALUE: &'static str = "Reset";
@@ -41,7 +45,9 @@ const DEFAULT_RESET_VALUE: &'static str = "Reset";
 #[deriving(PartialEq)]
 #[allow(dead_code)]
 enum InputType {
-    InputButton(Option<&'static str>),
+    InputSubmit,
+    InputReset,
+    InputButton,
     InputText,
     InputFile,
     InputImage,
@@ -55,8 +61,34 @@ pub struct HTMLInputElement {
     htmlelement: HTMLElement,
     input_type: Cell<InputType>,
     checked: Cell<bool>,
+    indeterminate: Cell<bool>,
     size: Cell<u32>,
     textinput: DOMRefCell<TextInput>,
+    activation_state: DOMRefCell<InputActivationState>,
+}
+
+#[jstraceable]
+#[must_root]
+struct InputActivationState {
+    indeterminate: bool,
+    checked: bool,
+    checked_radio: MutNullableJS<HTMLInputElement>,
+    // In case mutability changed
+    was_mutable: bool,
+    // In case the type changed
+    old_type: InputType,
+}
+
+impl InputActivationState {
+    fn new() -> InputActivationState {
+        InputActivationState {
+            indeterminate: false,
+            checked: false,
+            checked_radio: Default::default(),
+            was_mutable: false,
+            old_type: InputText
+        }
+    }
 }
 
 impl HTMLInputElementDerived for EventTarget {
@@ -73,8 +105,10 @@ impl HTMLInputElement {
             htmlelement: HTMLElement::new_inherited(HTMLInputElementTypeId, localName, prefix, document),
             input_type: Cell::new(InputText),
             checked: Cell::new(false),
+            indeterminate: Cell::new(false),
             size: Cell::new(DEFAULT_INPUT_SIZE),
             textinput: DOMRefCell::new(TextInput::new(Single, "".to_string())),
+            activation_state: DOMRefCell::new(InputActivationState::new())
         }
     }
 
@@ -110,9 +144,9 @@ impl LayoutHTMLInputElementHelpers for JS<HTMLInputElement> {
         match (*self.unsafe_get()).input_type.get() {
             InputCheckbox | InputRadio => "".to_string(),
             InputFile | InputImage => "".to_string(),
-            InputButton(ref default) => get_raw_attr_value(self)
-                                          .or_else(|| default.map(|v| v.to_string()))
-                                          .unwrap_or_else(|| "".to_string()),
+            InputButton => get_raw_attr_value(self).unwrap_or_else(|| "".to_string()),
+            InputSubmit => get_raw_attr_value(self).unwrap_or_else(|| DEFAULT_SUBMIT_VALUE.to_string()),
+            InputReset => get_raw_attr_value(self).unwrap_or_else(|| DEFAULT_RESET_VALUE.to_string()),
             InputPassword => {
                 let raw = get_raw_textinput_value(self);
                 String::from_char(raw.char_len(), '●')
@@ -149,6 +183,12 @@ impl<'a> HTMLInputElementMethods for JSRef<'a, HTMLInputElement> {
     // https://html.spec.whatwg.org/multipage/forms.html#dom-input-checked
     make_bool_setter!(SetChecked, "checked")
 
+    // https://html.spec.whatwg.org/multipage/forms.html#dom-input-readonly
+    make_bool_getter!(ReadOnly)
+
+    // https://html.spec.whatwg.org/multipage/forms.html#dom-input-readonly
+    make_bool_setter!(SetReadOnly, "readonly")
+
     // https://html.spec.whatwg.org/multipage/forms.html#dom-input-size
     make_uint_getter!(Size)
 
@@ -194,7 +234,7 @@ impl<'a> HTMLInputElementMethods for JSRef<'a, HTMLInputElement> {
     make_setter!(SetFormEnctype, "formenctype")
 
     // https://html.spec.whatwg.org/multipage/forms.html#dom-input-formmethod
-        make_enumerated_getter!(FormMethod, "get", "post" | "dialog")
+    make_enumerated_getter!(FormMethod, "get", "post" | "dialog")
 
     // https://html.spec.whatwg.org/multipage/forms.html#dom-input-formmethod
     make_setter!(SetFormMethod, "formmethod")
@@ -204,34 +244,59 @@ impl<'a> HTMLInputElementMethods for JSRef<'a, HTMLInputElement> {
 
     // https://html.spec.whatwg.org/multipage/forms.html#dom-input-formtarget
     make_setter!(SetFormTarget, "formtarget")
+
+    // https://html.spec.whatwg.org/multipage/forms.html#dom-input-indeterminate
+    fn Indeterminate(self) -> bool {
+        self.indeterminate.get()
+    }
+
+    // https://html.spec.whatwg.org/multipage/forms.html#dom-input-indeterminate
+    fn SetIndeterminate(self, val: bool) {
+        // FIXME #4079 this should change the appearance
+        self.indeterminate.set(val)
+    }
 }
 
 pub trait HTMLInputElementHelpers {
     fn force_relayout(self);
     fn radio_group_updated(self, group: Option<&str>);
-    fn get_radio_group(self) -> Option<String>;
+    fn get_radio_group_name(self) -> Option<String>;
     fn update_checked_state(self, checked: bool);
     fn get_size(&self) -> u32;
 }
 
 fn broadcast_radio_checked(broadcaster: JSRef<HTMLInputElement>, group: Option<&str>) {
     //TODO: if not in document, use root ancestor instead of document
+    let owner = broadcaster.form_owner().root();
     let doc = document_from_node(broadcaster).root();
-    let radios = doc.QuerySelectorAll("input[type=\"radio\"]".to_string()).unwrap().root();
-    let mut i = 0;
-    while i < radios.Length() {
-        let node = radios.Item(i).unwrap().root();
-        let radio: JSRef<HTMLInputElement> = HTMLInputElementCast::to_ref(*node).unwrap();
-        if radio != broadcaster {
-            //TODO: determine form owner
-            let other_group = radio.get_radio_group();
-            //TODO: ensure compatibility caseless match (https://html.spec.whatwg.org/multipage/infrastructure.html#compatibility-caseless)
-            let group_matches = other_group.as_ref().map(|group| group.as_slice()) == group.as_ref().map(|&group| &*group);
-            if group_matches && radio.Checked() {
-                radio.SetChecked(false);
-            }
+    let doc_node: JSRef<Node> = NodeCast::from_ref(*doc);
+
+    // There is no DOM tree manipulation here, so this is safe
+    let mut iter = unsafe {
+        doc_node.query_selector_iter("input[type=radio]".to_string()).unwrap()
+                .filter_map(|t| HTMLInputElementCast::to_ref(t))
+                .filter(|&r| in_same_group(r, owner.root_ref(), group) && broadcaster != r)
+    };
+    for r in iter {
+        if r.Checked() {
+            r.SetChecked(false);
         }
-        i += 1;
+    }
+}
+
+fn in_same_group<'a,'b>(other: JSRef<'a, HTMLInputElement>,
+                        owner: Option<JSRef<'b, HTMLFormElement>>,
+                        group: Option<&str>) -> bool {
+    let other_owner = other.form_owner().root();
+    let other_owner = other_owner.root_ref();
+    other.input_type.get() == InputRadio &&
+    // TODO Both a and b are in the same home subtree.
+    other_owner.equals(owner) &&
+    // TODO should be a unicode compatibility caseless match
+    match (other.get_radio_group_name(), group) {
+        (Some(ref s1), Some(s2)) => s1.as_slice() == s2,
+        (None, None) => true,
+        _ => false
     }
 }
 
@@ -248,8 +313,7 @@ impl<'a> HTMLInputElementHelpers for JSRef<'a, HTMLInputElement> {
         }
     }
 
-    // https://html.spec.whatwg.org/multipage/forms.html#radio-button-group
-    fn get_radio_group(self) -> Option<String> {
+    fn get_radio_group_name(self) -> Option<String> {
         //TODO: determine form owner
         let elem: JSRef<Element> = ElementCast::from_ref(self);
         elem.get_attribute(ns!(""), &atom!("name"))
@@ -261,7 +325,7 @@ impl<'a> HTMLInputElementHelpers for JSRef<'a, HTMLInputElement> {
         self.checked.set(checked);
         if self.input_type.get() == InputRadio && checked {
             broadcast_radio_checked(self,
-                                    self.get_radio_group()
+                                    self.get_radio_group_name()
                                         .as_ref()
                                         .map(|group| group.as_slice()));
         }
@@ -305,9 +369,9 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLInputElement> {
             &atom!("type") => {
                 let value = attr.value();
                 self.input_type.set(match value.as_slice() {
-                    "button" => InputButton(None),
-                    "submit" => InputButton(Some(DEFAULT_SUBMIT_VALUE)),
-                    "reset" => InputButton(Some(DEFAULT_RESET_VALUE)),
+                    "button" => InputButton,
+                    "submit" => InputSubmit,
+                    "reset" => InputReset,
                     "file" => InputFile,
                     "radio" => InputRadio,
                     "checkbox" => InputCheckbox,
@@ -315,7 +379,7 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLInputElement> {
                     _ => InputText,
                 });
                 if self.input_type.get() == InputRadio {
-                    self.radio_group_updated(self.get_radio_group()
+                    self.radio_group_updated(self.get_radio_group_name()
                                                  .as_ref()
                                                  .map(|group| group.as_slice()));
                 }
@@ -358,7 +422,7 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLInputElement> {
             &atom!("type") => {
                 if self.input_type.get() == InputRadio {
                     broadcast_radio_checked(*self,
-                                            self.get_radio_group()
+                                            self.get_radio_group_name()
                                                 .as_ref()
                                                 .map(|group| group.as_slice()));
                 }
@@ -419,16 +483,13 @@ impl<'a> VirtualMethods for JSRef<'a, HTMLInputElement> {
 
         if "click" == event.Type().as_slice() && !event.DefaultPrevented() {
             match self.input_type.get() {
-                InputCheckbox => self.SetChecked(!self.checked.get()),
                 InputRadio => self.SetChecked(true),
-                InputButton(Some(DEFAULT_SUBMIT_VALUE)) => {
-                    self.form_owner().map(|o| {
-                        o.root().submit(NotFromFormSubmitMethod, InputElement(self.clone()))
-                    });
-                }
                 _ => {}
             }
 
+            // TODO: Dispatch events for non activatable inputs
+            // https://html.spec.whatwg.org/multipage/forms.html#common-input-element-events
+
             //TODO: set the editing position for text inputs
 
             let doc = document_from_node(*self).root();
@@ -455,7 +516,7 @@ impl Reflectable for HTMLInputElement {
     }
 }
 
-impl<'a> FormOwner<'a> for JSRef<'a, HTMLInputElement> {
+impl<'a> FormControl<'a> for JSRef<'a, HTMLInputElement> {
     // FIXME: This is wrong (https://github.com/servo/servo/issues/3553)
     //        but we need html5ever to do it correctly
     fn form_owner(self) -> Option<Temporary<HTMLFormElement>> {
@@ -483,4 +544,168 @@ impl<'a> FormOwner<'a> for JSRef<'a, HTMLInputElement> {
     fn to_element(self) -> JSRef<'a, Element> {
         ElementCast::from_ref(self)
     }
+
+    // https://html.spec.whatwg.org/multipage/forms.html#concept-fe-mutable
+    fn mutable(self) -> bool {
+        // https://html.spec.whatwg.org/multipage/forms.html#the-input-element:concept-fe-mutable
+        // https://html.spec.whatwg.org/multipage/forms.html#the-readonly-attribute:concept-fe-mutable
+        !(self.Disabled() || self.ReadOnly())
+    }
+}
+
+
+impl<'a> Activatable for JSRef<'a, HTMLInputElement> {
+    fn as_element(&self) -> Temporary<Element> {
+        Temporary::from_rooted(ElementCast::from_ref(*self))
+    }
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#run-pre-click-activation-steps
+    fn pre_click_activation(&self) {
+        let mut cache = self.activation_state.borrow_mut();
+        let ty = self.input_type.get();
+        cache.old_type = ty;
+        cache.was_mutable = self.mutable();
+        if cache.was_mutable {
+            match ty {
+                // https://html.spec.whatwg.org/multipage/forms.html#submit-button-state-(type=submit):activation-behavior
+                // InputSubmit => (), // No behavior defined
+                InputCheckbox => {
+                    // https://html.spec.whatwg.org/multipage/forms.html#checkbox-state-(type=checkbox):pre-click-activation-steps
+                    // cache current values of `checked` and `indeterminate`
+                    // we may need to restore them later
+                    cache.indeterminate = self.Indeterminate();
+                    cache.checked = self.Checked();
+                    self.SetIndeterminate(false);
+                    self.SetChecked(!cache.checked);
+                },
+                // https://html.spec.whatwg.org/multipage/forms.html#radio-button-state-(type=radio):pre-click-activation-steps
+                InputRadio => {
+                    //TODO: if not in document, use root ancestor instead of document
+                    let owner = self.form_owner().root();
+                    let doc = document_from_node(*self).root();
+                    let doc_node: JSRef<Node> = NodeCast::from_ref(*doc);
+                    let group = self.get_radio_group_name();;
+
+                    // Safe since we only manipulate the DOM tree after finding an element
+                    let checked_member = unsafe {
+                        doc_node.query_selector_iter("input[type=radio]".to_string()).unwrap()
+                                .filter_map(|t| HTMLInputElementCast::to_ref(t))
+                                .filter(|&r| in_same_group(r, owner.root_ref(),
+                                                           group.as_ref().map(|gr| gr.as_slice())))
+                                .find(|r| r.Checked())
+                    };
+                    cache.checked_radio.assign(checked_member);
+                    self.SetChecked(true);
+                }
+                _ => ()
+            }
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#run-canceled-activation-steps
+    fn canceled_activation(&self) {
+        let cache = self.activation_state.borrow();
+        let ty = self.input_type.get();
+        if cache.old_type != ty  {
+            // Type changed, abandon ship
+            // https://www.w3.org/Bugs/Public/show_bug.cgi?id=27414
+            return;
+        }
+        match ty {
+            // https://html.spec.whatwg.org/multipage/forms.html#submit-button-state-(type=submit):activation-behavior
+            // InputSubmit => (), // No behavior defined
+            // https://html.spec.whatwg.org/multipage/forms.html#checkbox-state-(type=checkbox):canceled-activation-steps
+            InputCheckbox => {
+                // We want to restore state only if the element had been changed in the first place
+                if cache.was_mutable {
+                    self.SetIndeterminate(cache.indeterminate);
+                    self.SetChecked(cache.checked);
+                }
+            },
+            // https://html.spec.whatwg.org/multipage/forms.html#radio-button-state-(type=radio):canceled-activation-steps
+            InputRadio => {
+                // We want to restore state only if the element had been changed in the first place
+                if cache.was_mutable {
+                    let old_checked: Option<Root<HTMLInputElement>> = cache.checked_radio.get().root();
+                    let name = self.get_radio_group_name();
+                    match old_checked {
+                        Some(o) => {
+                            // Avoiding iterating through the whole tree here, instead
+                            // we can check if the conditions for radio group siblings apply
+                            if name == o.get_radio_group_name() && // TODO should be compatibility caseless
+                               self.form_owner() == o.form_owner() &&
+                               // TODO Both a and b are in the same home subtree
+                               o.input_type.get() == InputRadio {
+                                    o.SetChecked(true);
+                            } else {
+                                self.SetChecked(false);
+                            }
+                        },
+                        None => self.SetChecked(false)
+                    };
+                }
+            }
+            _ => ()
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/interaction.html#run-post-click-activation-steps
+    fn activation_behavior(&self) {
+        let ty = self.input_type.get();
+        if self.activation_state.borrow().old_type != ty {
+            // Type changed, abandon ship
+            // https://www.w3.org/Bugs/Public/show_bug.cgi?id=27414
+            return;
+        }
+        match ty {
+            InputSubmit => {
+                // https://html.spec.whatwg.org/multipage/forms.html#submit-button-state-(type=submit):activation-behavior
+                // FIXME (Manishearth): support document owners (needs ability to get parent browsing context)
+                if self.mutable() /* and document owner is fully active */ {
+                    self.form_owner().map(|o| {
+                        o.root().submit(NotFromFormSubmitMethod, InputElement(self.clone()))
+                    });
+                }
+            },
+            InputCheckbox | InputRadio => {
+                // https://html.spec.whatwg.org/multipage/forms.html#checkbox-state-(type=checkbox):activation-behavior
+                // https://html.spec.whatwg.org/multipage/forms.html#radio-button-state-(type=radio):activation-behavior
+                if self.mutable() {
+                    let win = window_from_node(*self).root();
+                    let event = Event::new(Window(*win),
+                                           "input".to_string(),
+                                           Bubbles, NotCancelable).root();
+                    event.set_trusted(true);
+                    let target: JSRef<EventTarget> = EventTargetCast::from_ref(*self);
+                    target.DispatchEvent(*event).ok();
+
+                    let event = Event::new(Window(*win),
+                                           "change".to_string(),
+                                           Bubbles, NotCancelable).root();
+                    event.set_trusted(true);
+                    let target: JSRef<EventTarget> = EventTargetCast::from_ref(*self);
+                    target.DispatchEvent(*event).ok();
+                }
+            },
+            _ => ()
+        }
+    }
+
+    // https://html.spec.whatwg.org/multipage/forms.html#implicit-submission
+    fn implicit_submission(&self, ctrlKey: bool, shiftKey: bool, altKey: bool, metaKey: bool) {
+        let doc = document_from_node(*self).root();
+        let node: JSRef<Node> = NodeCast::from_ref(*doc);
+        let owner = self.form_owner();
+        if owner.is_none() || ElementCast::from_ref(*self).click_in_progress() {
+            return;
+        }
+        // This is safe because we are stopping after finding the first element
+        // and only then performing actions which may modify the DOM tree
+        unsafe {
+            node.query_selector_iter("input[type=submit]".to_string()).unwrap()
+                .filter_map(|t| HTMLInputElementCast::to_ref(t))
+                .find(|r| r.form_owner() == owner)
+                .map(|s| s.synthetic_click_activation(ctrlKey, shiftKey, altKey, metaKey));
+        }
+    }
 }
diff --git a/servo/components/script/dom/macros.rs b/servo/components/script/dom/macros.rs
index 630a112c0320..a5789a5cc61a 100644
--- a/servo/components/script/dom/macros.rs
+++ b/servo/components/script/dom/macros.rs
@@ -211,3 +211,19 @@ macro_rules! error_event_handler(
         define_event_handler!(OnErrorEventHandlerNonNull, $event_type, $getter, $setter)
     )
 )
+
+// https://html.spec.whatwg.org/multipage/webappapis.html#globaleventhandlers
+// see webidls/EventHandler.webidl
+// As more methods get added, just update them here.
+macro_rules! global_event_handlers(
+    () => (
+        event_handler!(load, GetOnload, SetOnload)
+        global_event_handlers!(NoOnload)
+
+    );
+    (NoOnload) => (
+        event_handler!(click, GetOnclick, SetOnclick)
+        event_handler!(input, GetOninput, SetOninput)
+        event_handler!(change, GetOnchange, SetOnchange)
+    )
+)
diff --git a/servo/components/script/dom/node.rs b/servo/components/script/dom/node.rs
index 2c02ebc9b1ec..ef655cc1bc36 100644
--- a/servo/components/script/dom/node.rs
+++ b/servo/components/script/dom/node.rs
@@ -50,7 +50,7 @@ use devtools_traits::NodeInfo;
 use script_traits::UntrustedNodeAddress;
 use servo_util::geometry::Au;
 use servo_util::str::{DOMString, null_str_as_empty};
-use style::{parse_selector_list_from_str, matches};
+use style::{parse_selector_list_from_str, matches, SelectorList};
 
 use js::jsapi::{JSContext, JSObject, JSTracer, JSRuntime};
 use js::jsfriendapi;
@@ -124,7 +124,7 @@ impl NodeDerived for EventTarget {
 bitflags! {
     #[doc = "Flags for node items."]
     #[jstraceable]
-    flags NodeFlags: u8 {
+    flags NodeFlags: u16 {
         #[doc = "Specifies whether this node is in a document."]
         const IS_IN_DOC = 0x01,
         #[doc = "Specifies whether this node is in hover state."]
@@ -143,6 +143,12 @@ bitflags! {
         #[doc = "Specifies whether this node has descendants (inclusive of itself) which \
                  have changed since the last reflow."]
         const HAS_DIRTY_DESCENDANTS = 0x80,
+        // TODO: find a better place to keep this (#4105)
+        // https://critic.hoppipolla.co.uk/showcomment?chain=8873
+        // Perhaps using a Set in Document?
+        #[doc = "Specifies whether or not there is an authentic click in progress on \
+                 this element."]
+        const CLICK_IN_PROGRESS = 0x100,
     }
 }
 
@@ -377,6 +383,29 @@ impl<'a> PrivateNodeHelpers for JSRef<'a, Node> {
     }
 }
 
+pub struct QuerySelectorIterator<'a> {
+    selectors: SelectorList,
+    iterator: TreeIterator<'a>,
+}
+
+impl<'a> QuerySelectorIterator<'a> {
+    unsafe fn new(iter: TreeIterator<'a>, selectors: SelectorList) -> QuerySelectorIterator<'a> {
+        QuerySelectorIterator {
+            selectors: selectors,
+            iterator: iter,
+        }
+    }
+}
+
+impl<'a> Iterator<JSRef<'a, Node>> for QuerySelectorIterator<'a> {
+    fn next(&mut self) -> Option<JSRef<'a, Node>> {
+        let selectors = &self.selectors;
+        // TODO(cgaebel): Is it worth it to build a bloom filter here
+        // (instead of passing `None`)? Probably.
+        self.iterator.find(|node| node.is_element() && matches(selectors, node, &mut None))
+    }
+}
+
 pub trait NodeHelpers<'a> {
     fn ancestors(self) -> AncestorIterator<'a>;
     fn children(self) -> NodeChildrenIterator<'a>;
@@ -449,6 +478,7 @@ pub trait NodeHelpers<'a> {
     fn get_content_boxes(self) -> Vec<Rect<Au>>;
 
     fn query_selector(self, selectors: DOMString) -> Fallible<Option<Temporary<Element>>>;
+    unsafe fn query_selector_iter(self, selectors: DOMString) -> Fallible<QuerySelectorIterator<'a>>;
     fn query_selector_all(self, selectors: DOMString) -> Fallible<Temporary<NodeList>>;
 
     fn remove_self(self);
@@ -719,8 +749,10 @@ impl<'a> NodeHelpers<'a> for JSRef<'a, Node> {
         Ok(None)
     }
 
-    // http://dom.spec.whatwg.org/#dom-parentnode-queryselectorall
-    fn query_selector_all(self, selectors: DOMString) -> Fallible<Temporary<NodeList>> {
+    /// Get an iterator over all nodes which match a set of selectors
+    /// Be careful not to do anything which may manipulate the DOM tree whilst iterating, otherwise
+    /// the iterator may be invalidated
+    unsafe fn query_selector_iter(self, selectors: DOMString) -> Fallible<QuerySelectorIterator<'a>> {
         // Step 1.
         let nodes;
         let root = self.ancestors().last().unwrap_or(self.clone());
@@ -728,17 +760,25 @@ impl<'a> NodeHelpers<'a> for JSRef<'a, Node> {
             // Step 2.
             Err(()) => return Err(Syntax),
             // Step 3.
-            Ok(ref selectors) => {
-                nodes = root.traverse_preorder().filter(
-                    // TODO(cgaebel): Is it worth it to build a bloom filter here
-                    // (instead of passing `None`)? Probably.
-                    |node| node.is_element() && matches(selectors, node, &mut None)).collect()
+            Ok(selectors) => {
+                nodes = QuerySelectorIterator::new(root.traverse_preorder(), selectors);
             }
-        }
-        let window = window_from_node(self).root();
-        Ok(NodeList::new_simple_list(*window, nodes))
+        };
+        Ok(nodes)
     }
 
+    // http://dom.spec.whatwg.org/#dom-parentnode-queryselectorall
+    fn query_selector_all(self, selectors: DOMString) -> Fallible<Temporary<NodeList>> {
+        // Step 1.
+        unsafe {
+            self.query_selector_iter(selectors).map(|mut iter| {
+                let window = window_from_node(self).root();
+                NodeList::new_simple_list(*window, iter.collect())
+            })
+        }
+    }
+
+
     fn ancestors(self) -> AncestorIterator<'a> {
         AncestorIterator {
             current: self.parent_node.get().map(|node| (*node.root()).clone()),
diff --git a/servo/components/script/dom/webidls/EventHandler.webidl b/servo/components/script/dom/webidls/EventHandler.webidl
index 1278d7467fd6..de4914553023 100644
--- a/servo/components/script/dom/webidls/EventHandler.webidl
+++ b/servo/components/script/dom/webidls/EventHandler.webidl
@@ -23,6 +23,8 @@ typedef OnErrorEventHandlerNonNull? OnErrorEventHandler;
 interface GlobalEventHandlers {
            attribute EventHandler onclick;
            attribute EventHandler onload;
+           attribute EventHandler oninput;
+           attribute EventHandler onchange;
 };
 
 [NoInterfaceObject]
diff --git a/servo/components/script/dom/webidls/HTMLElement.webidl b/servo/components/script/dom/webidls/HTMLElement.webidl
index 10be66c62e3d..359ef11f0a77 100644
--- a/servo/components/script/dom/webidls/HTMLElement.webidl
+++ b/servo/components/script/dom/webidls/HTMLElement.webidl
@@ -23,7 +23,7 @@ interface HTMLElement : Element {
 
   // user interaction
            attribute boolean hidden;
-  //void click();
+  void click();
   //         attribute long tabIndex;
   //void focus();
   //void blur();
diff --git a/servo/components/script/dom/webidls/HTMLInputElement.webidl b/servo/components/script/dom/webidls/HTMLInputElement.webidl
index b69d8fcf4ff6..434da309f210 100644
--- a/servo/components/script/dom/webidls/HTMLInputElement.webidl
+++ b/servo/components/script/dom/webidls/HTMLInputElement.webidl
@@ -21,7 +21,7 @@ interface HTMLInputElement : HTMLElement {
   //         attribute boolean formNoValidate;
              attribute DOMString formTarget;
   //         attribute unsigned long height;
-  //         attribute boolean indeterminate;
+             attribute boolean indeterminate;
   //         attribute DOMString inputMode;
   //readonly attribute HTMLElement? list;
   //         attribute DOMString max;
@@ -32,7 +32,7 @@ interface HTMLInputElement : HTMLElement {
            attribute DOMString name;
   //         attribute DOMString pattern;
   //         attribute DOMString placeholder;
-  //         attribute boolean readOnly;
+           attribute boolean readOnly;
   //         attribute boolean required;
            attribute unsigned long size;
   //         attribute DOMString src;
diff --git a/servo/components/script/dom/window.rs b/servo/components/script/dom/window.rs
index 0e6e00ed2006..da0cc228b0a6 100644
--- a/servo/components/script/dom/window.rs
+++ b/servo/components/script/dom/window.rs
@@ -270,8 +270,7 @@ impl<'a> WindowMethods for JSRef<'a, Window> {
         self.performance.or_init(|| Performance::new(self))
     }
 
-    event_handler!(click, GetOnclick, SetOnclick)
-    event_handler!(load, GetOnload, SetOnload)
+    global_event_handlers!()
     event_handler!(unload, GetOnunload, SetOnunload)
     error_event_handler!(error, GetOnerror, SetOnerror)
 
diff --git a/servo/components/script/lib.rs b/servo/components/script/lib.rs
index 6edcb72ae45f..de1ddbe59879 100644
--- a/servo/components/script/lib.rs
+++ b/servo/components/script/lib.rs
@@ -82,6 +82,7 @@ pub mod dom {
     #[path="bindings/codegen/InterfaceTypes.rs"]
     pub mod types;
 
+    pub mod activation;
     pub mod attr;
     pub mod blob;
     pub mod browsercontext;
diff --git a/servo/components/script/script_task.rs b/servo/components/script/script_task.rs
index fdd4795ab252..28c7c2e8a0b9 100644
--- a/servo/components/script/script_task.rs
+++ b/servo/components/script/script_task.rs
@@ -10,7 +10,7 @@ use dom::bindings::codegen::Bindings::DocumentBinding::{DocumentMethods, Documen
 use dom::bindings::codegen::Bindings::EventBinding::EventMethods;
 use dom::bindings::codegen::Bindings::EventTargetBinding::EventTargetMethods;
 use dom::bindings::codegen::Bindings::WindowBinding::WindowMethods;
-use dom::bindings::codegen::InheritTypes::{EventTargetCast, NodeCast, EventCast};
+use dom::bindings::codegen::InheritTypes::{ElementCast, EventTargetCast, NodeCast, EventCast};
 use dom::bindings::conversions::{FromJSValConvertible, Empty};
 use dom::bindings::global;
 use dom::bindings::js::{JS, JSRef, RootCollection, Temporary, OptionalRootable};
@@ -18,8 +18,8 @@ use dom::bindings::trace::JSTraceable;
 use dom::bindings::utils::{wrap_for_same_compartment, pre_wrap};
 use dom::document::{Document, HTMLDocument, DocumentHelpers, FromParser};
 use dom::element::{Element, HTMLButtonElementTypeId, HTMLInputElementTypeId};
-use dom::element::{HTMLSelectElementTypeId, HTMLTextAreaElementTypeId, HTMLOptionElementTypeId};
-use dom::event::{Event, Bubbles, DoesNotBubble, Cancelable, NotCancelable};
+use dom::element::{HTMLSelectElementTypeId, HTMLTextAreaElementTypeId, HTMLOptionElementTypeId, ActivationElementHelpers};
+use dom::event::{Event, EventHelpers, Bubbles, DoesNotBubble, Cancelable, NotCancelable};
 use dom::uievent::UIEvent;
 use dom::eventtarget::{EventTarget, EventTargetHelpers};
 use dom::keyboardevent::KeyboardEvent;
@@ -893,9 +893,10 @@ impl ScriptTask {
                                           None, props.key_code).root();
         let event = EventCast::from_ref(*keyevent);
         let _ = target.DispatchEvent(event);
+        let mut prevented = event.DefaultPrevented();
 
         // https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#keys-cancelable-keys
-        if state != Released && props.is_printable() && !event.DefaultPrevented() {
+        if state != Released && props.is_printable() && !prevented {
             // https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#keypress-event-order
             let event = KeyboardEvent::new(*window, "keypress".to_string(), true, true, Some(*window),
                                            0, props.key.to_string(), props.code.to_string(),
@@ -904,9 +905,28 @@ impl ScriptTask {
                                            props.char_code, 0).root();
             let _ = target.DispatchEvent(EventCast::from_ref(*event));
 
+            let ev = EventCast::from_ref(*event);
+            prevented = ev.DefaultPrevented();
             // TODO: if keypress event is canceled, prevent firing input events
         }
 
+        // This behavior is unspecced
+        // We are supposed to dispatch synthetic click activation for Space and/or Return,
+        // however *when* we do it is up to us
+        // I'm dispatching it after the key event so the script has a chance to cancel it
+        // https://www.w3.org/Bugs/Public/show_bug.cgi?id=27337
+        match key {
+            Key::KeySpace if !prevented && state == Released => {
+                let maybe_elem: Option<JSRef<Element>> = ElementCast::to_ref(target);
+                maybe_elem.map(|el| el.as_maybe_activatable().map(|a| a.synthetic_click_activation(ctrl, alt, shift, meta)));
+            }
+            Key::KeyEnter if !prevented && state == Released => {
+                let maybe_elem: Option<JSRef<Element>> = ElementCast::to_ref(target);
+                maybe_elem.map(|el| el.as_maybe_activatable().map(|a| a.implicit_submission(ctrl, alt, shift, meta)));
+            }
+            _ => ()
+        }
+
         window.flush_layout();
     }
 
@@ -1018,8 +1038,11 @@ impl ScriptTask {
                                     Event::new(global::Window(*window),
                                                "click".to_string(),
                                                Bubbles, Cancelable).root();
-                                let eventtarget: JSRef<EventTarget> = EventTargetCast::from_ref(node);
-                                let _ = eventtarget.dispatch_event_with_target(None, *event);
+                                // https://dvcs.w3.org/hg/dom3events/raw-file/tip/html/DOM3-Events.html#trusted-events
+                                event.set_trusted(true);
+                                // https://html.spec.whatwg.org/multipage/interaction.html#run-authentic-click-activation-steps
+                                let el = ElementCast::to_ref(node).unwrap(); // is_element() check already exists above
+                                el.authentic_click_activation(*event);
 
                                 doc.commit_focus_transaction();
                                 window.flush_layout();
diff --git a/servo/tests/html/test-synthetic-click-activation.html b/servo/tests/html/test-synthetic-click-activation.html
new file mode 100644
index 000000000000..011914895a7a
--- /dev/null
+++ b/servo/tests/html/test-synthetic-click-activation.html
@@ -0,0 +1,31 @@
+<style>
+</style>
+<form action="http://example.com" method="get">
+<div><input type="checkbox"></div>
+<div><input type="submit"><input type="reset"></div>
+<div><input type="checkbox"></div>
+<div><input type="checkbox" checked></div>
+<div>group 1
+  <div><input type="radio"></div>
+  <div><input type="radio" checked></div>
+</div>
+<div>group 2
+  <div><input type="radio" name="a" checked></div>
+  <div><input type="radio" name="a"></div>
+</div>
+</form>
+<br>
+Use the buttons below to shift "fake" focus and trigger click events. The first form widget is initually focused.
+<br>
+<button type=button id="left">Shift fake focus left</button><br>
+<button type=button id="right">Shift fake focus right</button><br>
+<button type=button id="click">Trigger synthetic click</button><br>
+
+
+<script>
+i = 0;
+tags = document.getElementsByTagName("input");
+document.getElementById("left").onclick=function(){i--;}
+document.getElementById("right").onclick=function(){i++;}
+document.getElementById("click").onclick=function(){tags[i].click()}
+</script>