diff --git a/src/platform_impl/web/event_loop/runner.rs b/src/platform_impl/web/event_loop/runner.rs
index cadd1dcd..f704346e 100644
--- a/src/platform_impl/web/event_loop/runner.rs
+++ b/src/platform_impl/web/event_loop/runner.rs
@@ -16,6 +16,7 @@ impl<T> Clone for Shared<T> {
 pub struct Execution<T> {
     runner: RefCell<Option<Runner<T>>>,
     events: RefCell<VecDeque<Event<T>>>,
+    id: RefCell<u32>,
 }
 
 struct Runner<T> {
@@ -39,6 +40,7 @@ impl<T: 'static> Shared<T> {
         Shared(Rc::new(Execution {
             runner: RefCell::new(None),
             events: RefCell::new(VecDeque::new()),
+            id: RefCell::new(0),
         }))
     }
 
@@ -53,6 +55,15 @@ impl<T: 'static> Shared<T> {
         backend::on_unload(move || close_instance.handle_unload());
     }
 
+    // Generate a strictly increasing ID
+    // This is used to differentiate windows when handling events
+    pub fn generate_id(&self) -> u32 {
+        let mut id = self.0.id.borrow_mut();
+        *id += 1;
+
+        *id
+    }
+
     // Add an event to the event loop runner
     //
     // It will determine if the event should be immediately sent to the user or buffered for later
diff --git a/src/platform_impl/web/event_loop/window_target.rs b/src/platform_impl/web/event_loop/window_target.rs
index 17ba26ae..e7bab388 100644
--- a/src/platform_impl/web/event_loop/window_target.rs
+++ b/src/platform_impl/web/event_loop/window_target.rs
@@ -31,11 +31,16 @@ impl<T> WindowTarget<T> {
         self.runner.set_listener(event_handler);
     }
 
-    pub fn register(&self, canvas: &mut backend::Canvas) {
+    pub fn generate_id(&self) -> window::Id {
+        window::Id(self.runner.generate_id())
+    }
+
+    pub fn register(&self, canvas: &mut backend::Canvas, id: window::Id) {
         let runner = self.runner.clone();
+
         canvas.on_blur(move || {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::Focused(false),
             });
         });
@@ -43,7 +48,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_focus(move || {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::Focused(true),
             });
         });
@@ -51,7 +56,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_keyboard_press(move |scancode, virtual_keycode, modifiers| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::KeyboardInput {
                     device_id: DeviceId(unsafe { device::Id::dummy() }),
                     input: KeyboardInput {
@@ -67,7 +72,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_keyboard_release(move |scancode, virtual_keycode, modifiers| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::KeyboardInput {
                     device_id: DeviceId(unsafe { device::Id::dummy() }),
                     input: KeyboardInput {
@@ -83,7 +88,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_received_character(move |char_code| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::ReceivedCharacter(char_code),
             });
         });
@@ -91,7 +96,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_cursor_leave(move |pointer_id| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::CursorLeft {
                     device_id: DeviceId(device::Id(pointer_id)),
                 },
@@ -101,7 +106,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_cursor_enter(move |pointer_id| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::CursorEntered {
                     device_id: DeviceId(device::Id(pointer_id)),
                 },
@@ -111,7 +116,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_cursor_move(move |pointer_id, position, modifiers| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::CursorMoved {
                     device_id: DeviceId(device::Id(pointer_id)),
                     position,
@@ -123,7 +128,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_mouse_press(move |pointer_id, button, modifiers| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::MouseInput {
                     device_id: DeviceId(device::Id(pointer_id)),
                     state: ElementState::Pressed,
@@ -136,7 +141,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_mouse_release(move |pointer_id, button, modifiers| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::MouseInput {
                     device_id: DeviceId(device::Id(pointer_id)),
                     state: ElementState::Released,
@@ -149,7 +154,7 @@ impl<T> WindowTarget<T> {
         let runner = self.runner.clone();
         canvas.on_mouse_wheel(move |pointer_id, delta, modifiers| {
             runner.send_event(Event::WindowEvent {
-                window_id: WindowId(window::Id),
+                window_id: WindowId(id),
                 event: WindowEvent::MouseWheel {
                     device_id: DeviceId(device::Id(pointer_id)),
                     delta,
diff --git a/src/platform_impl/web/stdweb/canvas.rs b/src/platform_impl/web/stdweb/canvas.rs
index 1cd99e7e..cf670471 100644
--- a/src/platform_impl/web/stdweb/canvas.rs
+++ b/src/platform_impl/web/stdweb/canvas.rs
@@ -13,7 +13,7 @@ use stdweb::web::event::{
 };
 use stdweb::web::html_element::CanvasElement;
 use stdweb::web::{
-    document, window, EventListenerHandle, IChildNode, IElement, IEventTarget, IHtmlElement, INode,
+    document, window, EventListenerHandle, IChildNode, IElement, IEventTarget, IHtmlElement,
 };
 
 pub struct Canvas {
diff --git a/src/platform_impl/web/window.rs b/src/platform_impl/web/window.rs
index 7a8f740a..be9a9082 100644
--- a/src/platform_impl/web/window.rs
+++ b/src/platform_impl/web/window.rs
@@ -15,6 +15,7 @@ pub struct Window {
     canvas: backend::Canvas,
     previous_pointer: RefCell<&'static str>,
     position: RefCell<LogicalPosition>,
+    id: Id,
 }
 
 impl Window {
@@ -25,19 +26,22 @@ impl Window {
     ) -> Result<Self, RootOE> {
         let runner = target.runner.clone();
 
+        let id = target.generate_id();
+
         let mut canvas = backend::Canvas::create(move || {
             runner.send_event(Event::WindowEvent {
-                window_id: RootWI(Id),
+                window_id: RootWI(id),
                 event: WindowEvent::RedrawRequested,
             })
         })?;
 
-        target.register(&mut canvas);
+        target.register(&mut canvas, id);
 
         let window = Window {
             canvas,
             previous_pointer: RefCell::new("auto"),
             position: RefCell::new(LogicalPosition { x: 0.0, y: 0.0 }),
+            id,
         };
 
         window.set_inner_size(attr.inner_size.unwrap_or(LogicalSize {
@@ -250,17 +254,16 @@ impl Window {
 
     #[inline]
     pub fn id(&self) -> Id {
-        // TODO ?
-        unsafe { Id::dummy() }
+        return self.id;
     }
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct Id;
+pub struct Id(pub(crate) u32);
 
 impl Id {
     pub unsafe fn dummy() -> Id {
-        Id
+        Id(0)
     }
 }