diff --git a/crates/gpui2/src/action.rs b/crates/gpui2/src/action.rs
index 638e5c6ca3..84843c9876 100644
--- a/crates/gpui2/src/action.rs
+++ b/crates/gpui2/src/action.rs
@@ -4,7 +4,7 @@ use collections::{HashMap, HashSet};
 use serde::Deserialize;
 use std::any::{type_name, Any};
 
-pub trait Action: Any + Send {
+pub trait Action: 'static {
     fn qualified_name() -> SharedString
     where
         Self: Sized;
@@ -19,7 +19,7 @@ pub trait Action: Any + Send {
 
 impl<A> Action for A
 where
-    A: for<'a> Deserialize<'a> + PartialEq + Any + Send + Clone + Default,
+    A: for<'a> Deserialize<'a> + PartialEq + Clone + Default + 'static,
 {
     fn qualified_name() -> SharedString {
         type_name::<A>().into()
diff --git a/crates/gpui2/src/app.rs b/crates/gpui2/src/app.rs
index 265ce59a02..48a9324b05 100644
--- a/crates/gpui2/src/app.rs
+++ b/crates/gpui2/src/app.rs
@@ -13,11 +13,12 @@ use smallvec::SmallVec;
 pub use test_context::*;
 
 use crate::{
-    current_platform, image_cache::ImageCache, Action, AnyBox, AnyView, AppMetadata, AssetSource,
-    BackgroundExecutor, ClipboardItem, Context, DispatchPhase, DisplayId, FocusEvent, FocusHandle,
-    FocusId, ForegroundExecutor, KeyBinding, Keymap, LayoutId, Pixels, Platform, Point, Render,
-    SharedString, SubscriberSet, Subscription, SvgRenderer, Task, TextStyle, TextStyleRefinement,
-    TextSystem, View, Window, WindowContext, WindowHandle, WindowId,
+    current_platform, image_cache::ImageCache, Action, AnyBox, AnyView, AnyWindowHandle,
+    AppMetadata, AssetSource, BackgroundExecutor, ClipboardItem, Context, DispatchPhase, DisplayId,
+    Entity, FocusEvent, FocusHandle, FocusId, ForegroundExecutor, KeyBinding, Keymap, LayoutId,
+    Pixels, Platform, Point, Render, SharedString, SubscriberSet, Subscription, SvgRenderer, Task,
+    TextStyle, TextStyleRefinement, TextSystem, View, Window, WindowContext, WindowHandle,
+    WindowId,
 };
 use anyhow::{anyhow, Result};
 use collections::{HashMap, HashSet, VecDeque};
@@ -114,8 +115,8 @@ type ActionBuilder = fn(json: Option<serde_json::Value>) -> anyhow::Result<Box<d
 type FrameCallback = Box<dyn FnOnce(&mut WindowContext)>;
 type Handler = Box<dyn FnMut(&mut AppContext) -> bool + 'static>;
 type Listener = Box<dyn FnMut(&dyn Any, &mut AppContext) -> bool + 'static>;
-type QuitHandler = Box<dyn FnMut(&mut AppContext) -> LocalBoxFuture<'static, ()> + 'static>;
-type ReleaseListener = Box<dyn FnMut(&mut dyn Any, &mut AppContext) + 'static>;
+type QuitHandler = Box<dyn FnOnce(&mut AppContext) -> LocalBoxFuture<'static, ()> + 'static>;
+type ReleaseListener = Box<dyn FnOnce(&mut dyn Any, &mut AppContext) + 'static>;
 
 pub struct AppContext {
     this: Weak<RefCell<AppContext>>,
@@ -214,10 +215,9 @@ impl AppContext {
     pub fn quit(&mut self) {
         let mut futures = Vec::new();
 
-        self.quit_observers.clone().retain(&(), |observer| {
+        for observer in self.quit_observers.remove(&()) {
             futures.push(observer(self));
-            true
-        });
+        }
 
         self.windows.clear();
         self.flush_effects();
@@ -255,37 +255,31 @@ impl AppContext {
         result
     }
 
-    pub(crate) fn read_window<R>(
-        &self,
-        id: WindowId,
-        read: impl FnOnce(&WindowContext) -> R,
-    ) -> Result<R> {
-        let window = self
-            .windows
-            .get(id)
-            .ok_or_else(|| anyhow!("window not found"))?
-            .as_ref()
-            .unwrap();
-        Ok(read(&WindowContext::immutable(self, &window)))
+    pub fn windows(&self) -> Vec<AnyWindowHandle> {
+        self.windows
+            .values()
+            .filter_map(|window| Some(window.as_ref()?.handle.clone()))
+            .collect()
     }
 
     pub(crate) fn update_window<R>(
         &mut self,
-        id: WindowId,
-        update: impl FnOnce(&mut WindowContext) -> R,
+        handle: AnyWindowHandle,
+        update: impl FnOnce(AnyView, &mut WindowContext) -> R,
     ) -> Result<R> {
         self.update(|cx| {
             let mut window = cx
                 .windows
-                .get_mut(id)
+                .get_mut(handle.id)
                 .ok_or_else(|| anyhow!("window not found"))?
                 .take()
                 .unwrap();
 
-            let result = update(&mut WindowContext::mutable(cx, &mut window));
+            let root_view = window.root_view.clone().unwrap();
+            let result = update(root_view, &mut WindowContext::new(cx, &mut window));
 
             cx.windows
-                .get_mut(id)
+                .get_mut(handle.id)
                 .ok_or_else(|| anyhow!("window not found"))?
                 .replace(window);
 
@@ -305,7 +299,7 @@ impl AppContext {
             let id = cx.windows.insert(None);
             let handle = WindowHandle::new(id);
             let mut window = Window::new(handle.into(), options, cx);
-            let root_view = build_root_view(&mut WindowContext::mutable(cx, &mut window));
+            let root_view = build_root_view(&mut WindowContext::new(cx, &mut window));
             window.root_view.replace(root_view.into());
             cx.windows.get_mut(id).unwrap().replace(window);
             handle
@@ -386,8 +380,11 @@ impl AppContext {
                         self.apply_notify_effect(emitter);
                     }
                     Effect::Emit { emitter, event } => self.apply_emit_effect(emitter, event),
-                    Effect::FocusChanged { window_id, focused } => {
-                        self.apply_focus_changed_effect(window_id, focused);
+                    Effect::FocusChanged {
+                        window_handle,
+                        focused,
+                    } => {
+                        self.apply_focus_changed_effect(window_handle, focused);
                     }
                     Effect::Refresh => {
                         self.apply_refresh_effect();
@@ -407,18 +404,18 @@ impl AppContext {
         let dirty_window_ids = self
             .windows
             .iter()
-            .filter_map(|(window_id, window)| {
+            .filter_map(|(_, window)| {
                 let window = window.as_ref().unwrap();
                 if window.dirty {
-                    Some(window_id)
+                    Some(window.handle.clone())
                 } else {
                     None
                 }
             })
             .collect::<SmallVec<[_; 8]>>();
 
-        for dirty_window_id in dirty_window_ids {
-            self.update_window(dirty_window_id, |cx| cx.draw()).unwrap();
+        for dirty_window_handle in dirty_window_ids {
+            dirty_window_handle.update(self, |_, cx| cx.draw()).unwrap();
         }
     }
 
@@ -435,7 +432,7 @@ impl AppContext {
             for (entity_id, mut entity) in dropped {
                 self.observers.remove(&entity_id);
                 self.event_listeners.remove(&entity_id);
-                for mut release_callback in self.release_listeners.remove(&entity_id) {
+                for release_callback in self.release_listeners.remove(&entity_id) {
                     release_callback(entity.as_mut(), self);
                 }
             }
@@ -446,27 +443,27 @@ impl AppContext {
     /// For now, we simply blur the window if this happens, but we may want to support invoking
     /// a window blur handler to restore focus to some logical element.
     fn release_dropped_focus_handles(&mut self) {
-        let window_ids = self.windows.keys().collect::<SmallVec<[_; 8]>>();
-        for window_id in window_ids {
-            self.update_window(window_id, |cx| {
-                let mut blur_window = false;
-                let focus = cx.window.focus;
-                cx.window.focus_handles.write().retain(|handle_id, count| {
-                    if count.load(SeqCst) == 0 {
-                        if focus == Some(handle_id) {
-                            blur_window = true;
+        for window_handle in self.windows() {
+            window_handle
+                .update(self, |_, cx| {
+                    let mut blur_window = false;
+                    let focus = cx.window.focus;
+                    cx.window.focus_handles.write().retain(|handle_id, count| {
+                        if count.load(SeqCst) == 0 {
+                            if focus == Some(handle_id) {
+                                blur_window = true;
+                            }
+                            false
+                        } else {
+                            true
                         }
-                        false
-                    } else {
-                        true
-                    }
-                });
+                    });
 
-                if blur_window {
-                    cx.blur();
-                }
-            })
-            .unwrap();
+                    if blur_window {
+                        cx.blur();
+                    }
+                })
+                .unwrap();
         }
     }
 
@@ -483,30 +480,35 @@ impl AppContext {
             .retain(&emitter, |handler| handler(event.as_ref(), self));
     }
 
-    fn apply_focus_changed_effect(&mut self, window_id: WindowId, focused: Option<FocusId>) {
-        self.update_window(window_id, |cx| {
-            if cx.window.focus == focused {
-                let mut listeners = mem::take(&mut cx.window.focus_listeners);
-                let focused =
-                    focused.map(|id| FocusHandle::for_id(id, &cx.window.focus_handles).unwrap());
-                let blurred = cx
-                    .window
-                    .last_blur
-                    .take()
-                    .unwrap()
-                    .and_then(|id| FocusHandle::for_id(id, &cx.window.focus_handles));
-                if focused.is_some() || blurred.is_some() {
-                    let event = FocusEvent { focused, blurred };
-                    for listener in &listeners {
-                        listener(&event, cx);
+    fn apply_focus_changed_effect(
+        &mut self,
+        window_handle: AnyWindowHandle,
+        focused: Option<FocusId>,
+    ) {
+        window_handle
+            .update(self, |_, cx| {
+                if cx.window.focus == focused {
+                    let mut listeners = mem::take(&mut cx.window.focus_listeners);
+                    let focused = focused
+                        .map(|id| FocusHandle::for_id(id, &cx.window.focus_handles).unwrap());
+                    let blurred = cx
+                        .window
+                        .last_blur
+                        .take()
+                        .unwrap()
+                        .and_then(|id| FocusHandle::for_id(id, &cx.window.focus_handles));
+                    if focused.is_some() || blurred.is_some() {
+                        let event = FocusEvent { focused, blurred };
+                        for listener in &listeners {
+                            listener(&event, cx);
+                        }
                     }
-                }
 
-                listeners.extend(cx.window.focus_listeners.drain(..));
-                cx.window.focus_listeners = listeners;
-            }
-        })
-        .ok();
+                    listeners.extend(cx.window.focus_listeners.drain(..));
+                    cx.window.focus_listeners = listeners;
+                }
+            })
+            .ok();
     }
 
     fn apply_refresh_effect(&mut self) {
@@ -680,6 +682,24 @@ impl AppContext {
         self.globals_by_type.insert(global_type, lease.global);
     }
 
+    pub fn observe_release<E, T>(
+        &mut self,
+        handle: &E,
+        on_release: impl FnOnce(&mut T, &mut AppContext) + 'static,
+    ) -> Subscription
+    where
+        E: Entity<T>,
+        T: 'static,
+    {
+        self.release_listeners.insert(
+            handle.entity_id(),
+            Box::new(move |entity, cx| {
+                let entity = entity.downcast_mut().expect("invalid entity type");
+                on_release(entity, cx)
+            }),
+        )
+    }
+
     pub(crate) fn push_text_style(&mut self, text_style: TextStyleRefinement) {
         self.text_style_stack.push(text_style);
     }
@@ -733,7 +753,6 @@ impl AppContext {
 }
 
 impl Context for AppContext {
-    type ModelContext<'a, T> = ModelContext<'a, T>;
     type Result<T> = T;
 
     /// Build an entity that is owned by the application. The given function will be invoked with
@@ -741,11 +760,11 @@ impl Context for AppContext {
     /// which can be used to access the entity in a context.
     fn build_model<T: 'static>(
         &mut self,
-        build_model: impl FnOnce(&mut Self::ModelContext<'_, T>) -> T,
+        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
     ) -> Model<T> {
         self.update(|cx| {
             let slot = cx.entities.reserve();
-            let entity = build_model(&mut ModelContext::mutable(cx, slot.downgrade()));
+            let entity = build_model(&mut ModelContext::new(cx, slot.downgrade()));
             cx.entities.insert(slot, entity)
         })
     }
@@ -755,18 +774,38 @@ impl Context for AppContext {
     fn update_model<T: 'static, R>(
         &mut self,
         model: &Model<T>,
-        update: impl FnOnce(&mut T, &mut Self::ModelContext<'_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
     ) -> R {
         self.update(|cx| {
             let mut entity = cx.entities.lease(model);
-            let result = update(
-                &mut entity,
-                &mut ModelContext::mutable(cx, model.downgrade()),
-            );
+            let result = update(&mut entity, &mut ModelContext::new(cx, model.downgrade()));
             cx.entities.end_lease(entity);
             result
         })
     }
+
+    fn update_window<T, F>(&mut self, handle: AnyWindowHandle, update: F) -> Result<T>
+    where
+        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
+    {
+        self.update(|cx| {
+            let mut window = cx
+                .windows
+                .get_mut(handle.id)
+                .ok_or_else(|| anyhow!("window not found"))?
+                .take()
+                .unwrap();
+
+            let root_view = window.root_view.clone().unwrap();
+            let result = update(root_view, &mut WindowContext::new(cx, &mut window));
+            cx.windows
+                .get_mut(handle.id)
+                .ok_or_else(|| anyhow!("window not found"))?
+                .replace(window);
+
+            Ok(result)
+        })
+    }
 }
 
 /// These effects are processed at the end of each application update cycle.
@@ -779,7 +818,7 @@ pub(crate) enum Effect {
         event: Box<dyn Any>,
     },
     FocusChanged {
-        window_id: WindowId,
+        window_handle: AnyWindowHandle,
         focused: Option<FocusId>,
     },
     Refresh,
diff --git a/crates/gpui2/src/app/async_context.rs b/crates/gpui2/src/app/async_context.rs
index fb941b91b8..01af7ae194 100644
--- a/crates/gpui2/src/app/async_context.rs
+++ b/crates/gpui2/src/app/async_context.rs
@@ -1,8 +1,8 @@
 use crate::{
-    AnyWindowHandle, AppContext, BackgroundExecutor, Context, ForegroundExecutor, Model,
-    ModelContext, Result, Task, WindowContext,
+    AnyView, AnyWindowHandle, AppContext, BackgroundExecutor, Context, ForegroundExecutor, Model,
+    ModelContext, Render, Result, Task, View, ViewContext, VisualContext, WindowContext,
 };
-use anyhow::anyhow;
+use anyhow::{anyhow, Context as _};
 use derive_more::{Deref, DerefMut};
 use std::{cell::RefCell, future::Future, rc::Weak};
 
@@ -14,12 +14,11 @@ pub struct AsyncAppContext {
 }
 
 impl Context for AsyncAppContext {
-    type ModelContext<'a, T> = ModelContext<'a, T>;
     type Result<T> = Result<T>;
 
     fn build_model<T: 'static>(
         &mut self,
-        build_model: impl FnOnce(&mut Self::ModelContext<'_, T>) -> T,
+        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
     ) -> Self::Result<Model<T>>
     where
         T: 'static,
@@ -35,7 +34,7 @@ impl Context for AsyncAppContext {
     fn update_model<T: 'static, R>(
         &mut self,
         handle: &Model<T>,
-        update: impl FnOnce(&mut T, &mut Self::ModelContext<'_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
     ) -> Self::Result<R> {
         let app = self
             .app
@@ -44,6 +43,15 @@ impl Context for AsyncAppContext {
         let mut app = app.borrow_mut();
         Ok(app.update_model(handle, update))
     }
+
+    fn update_window<T, F>(&mut self, window: AnyWindowHandle, f: F) -> Result<T>
+    where
+        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
+    {
+        let app = self.app.upgrade().context("app was released")?;
+        let mut lock = app.borrow_mut();
+        lock.update_window(window, f)
+    }
 }
 
 impl AsyncAppContext {
@@ -74,30 +82,17 @@ impl AsyncAppContext {
         Ok(f(&mut *lock))
     }
 
-    pub fn read_window<R>(
-        &self,
-        handle: AnyWindowHandle,
-        update: impl FnOnce(&WindowContext) -> R,
-    ) -> Result<R> {
-        let app = self
-            .app
-            .upgrade()
-            .ok_or_else(|| anyhow!("app was released"))?;
-        let app_context = app.borrow();
-        app_context.read_window(handle.id, update)
-    }
-
     pub fn update_window<R>(
         &self,
         handle: AnyWindowHandle,
-        update: impl FnOnce(&mut WindowContext) -> R,
+        update: impl FnOnce(AnyView, &mut WindowContext) -> R,
     ) -> Result<R> {
         let app = self
             .app
             .upgrade()
             .ok_or_else(|| anyhow!("app was released"))?;
         let mut app_context = app.borrow_mut();
-        app_context.update_window(handle.id, update)
+        app_context.update_window(handle, update)
     }
 
     pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncAppContext) -> Fut) -> Task<R>
@@ -161,22 +156,22 @@ impl AsyncWindowContext {
         Self { app, window }
     }
 
-    pub fn update<R>(&self, update: impl FnOnce(&mut WindowContext) -> R) -> Result<R> {
+    pub fn update<R>(
+        &mut self,
+        update: impl FnOnce(AnyView, &mut WindowContext) -> R,
+    ) -> Result<R> {
         self.app.update_window(self.window, update)
     }
 
-    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut WindowContext) + Send + 'static) {
-        self.app
-            .update_window(self.window, |cx| cx.on_next_frame(f))
-            .ok();
+    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
+        self.window.update(self, |_, cx| cx.on_next_frame(f)).ok();
     }
 
     pub fn read_global<G: 'static, R>(
-        &self,
+        &mut self,
         read: impl FnOnce(&G, &WindowContext) -> R,
     ) -> Result<R> {
-        self.app
-            .read_window(self.window, |cx| read(cx.global(), cx))
+        self.window.update(self, |_, cx| read(cx.global(), cx))
     }
 
     pub fn update_global<G, R>(
@@ -186,32 +181,79 @@ impl AsyncWindowContext {
     where
         G: 'static,
     {
-        self.app
-            .update_window(self.window, |cx| cx.update_global(update))
+        self.window.update(self, |_, cx| cx.update_global(update))
+    }
+
+    pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncWindowContext) -> Fut + 'static) -> Task<R>
+    where
+        Fut: Future<Output = R> + 'static,
+        R: 'static,
+    {
+        let this = self.clone();
+        self.foreground_executor.spawn(async move { f(this).await })
     }
 }
 
 impl Context for AsyncWindowContext {
-    type ModelContext<'a, T> = ModelContext<'a, T>;
     type Result<T> = Result<T>;
 
     fn build_model<T>(
         &mut self,
-        build_model: impl FnOnce(&mut Self::ModelContext<'_, T>) -> T,
+        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
     ) -> Result<Model<T>>
     where
         T: 'static,
     {
-        self.app
-            .update_window(self.window, |cx| cx.build_model(build_model))
+        self.window
+            .update(self, |_, cx| cx.build_model(build_model))
     }
 
     fn update_model<T: 'static, R>(
         &mut self,
         handle: &Model<T>,
-        update: impl FnOnce(&mut T, &mut Self::ModelContext<'_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
     ) -> Result<R> {
-        self.app
-            .update_window(self.window, |cx| cx.update_model(handle, update))
+        self.window
+            .update(self, |_, cx| cx.update_model(handle, update))
+    }
+
+    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
+    where
+        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
+    {
+        self.app.update_window(window, update)
+    }
+}
+
+impl VisualContext for AsyncWindowContext {
+    fn build_view<V>(
+        &mut self,
+        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
+    ) -> Self::Result<View<V>>
+    where
+        V: 'static,
+    {
+        self.window
+            .update(self, |_, cx| cx.build_view(build_view_state))
+    }
+
+    fn update_view<V: 'static, R>(
+        &mut self,
+        view: &View<V>,
+        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
+    ) -> Self::Result<R> {
+        self.window
+            .update(self, |_, cx| cx.update_view(view, update))
+    }
+
+    fn replace_root_view<V>(
+        &mut self,
+        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
+    ) -> Self::Result<View<V>>
+    where
+        V: Render,
+    {
+        self.window
+            .update(self, |_, cx| cx.replace_root_view(build_view))
     }
 }
diff --git a/crates/gpui2/src/app/entity_map.rs b/crates/gpui2/src/app/entity_map.rs
index 4a4b178e1e..e626f8c409 100644
--- a/crates/gpui2/src/app/entity_map.rs
+++ b/crates/gpui2/src/app/entity_map.rs
@@ -1,4 +1,4 @@
-use crate::{private::Sealed, AnyBox, AppContext, Context, Entity};
+use crate::{private::Sealed, AnyBox, AppContext, Context, Entity, ModelContext};
 use anyhow::{anyhow, Result};
 use derive_more::{Deref, DerefMut};
 use parking_lot::{RwLock, RwLockUpgradableReadGuard};
@@ -169,6 +169,10 @@ impl AnyModel {
         self.entity_id
     }
 
+    pub fn entity_type(&self) -> TypeId {
+        self.entity_type
+    }
+
     pub fn downgrade(&self) -> AnyWeakModel {
         AnyWeakModel {
             entity_id: self.entity_id,
@@ -329,7 +333,7 @@ impl<T: 'static> Model<T> {
     pub fn update<C, R>(
         &self,
         cx: &mut C,
-        update: impl FnOnce(&mut T, &mut C::ModelContext<'_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
     ) -> C::Result<R>
     where
         C: Context,
@@ -475,7 +479,7 @@ impl<T: 'static> WeakModel<T> {
     pub fn update<C, R>(
         &self,
         cx: &mut C,
-        update: impl FnOnce(&mut T, &mut C::ModelContext<'_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
     ) -> Result<R>
     where
         C: Context,
diff --git a/crates/gpui2/src/app/model_context.rs b/crates/gpui2/src/app/model_context.rs
index f6982cdc1f..cb25adfb63 100644
--- a/crates/gpui2/src/app/model_context.rs
+++ b/crates/gpui2/src/app/model_context.rs
@@ -1,7 +1,8 @@
 use crate::{
-    AppContext, AsyncAppContext, Context, Effect, Entity, EntityId, EventEmitter, Model, Reference,
-    Subscription, Task, WeakModel,
+    AnyView, AnyWindowHandle, AppContext, AsyncAppContext, Context, Effect, Entity, EntityId,
+    EventEmitter, Model, Subscription, Task, WeakModel, WindowContext,
 };
+use anyhow::Result;
 use derive_more::{Deref, DerefMut};
 use futures::FutureExt;
 use std::{
@@ -14,16 +15,13 @@ use std::{
 pub struct ModelContext<'a, T> {
     #[deref]
     #[deref_mut]
-    app: Reference<'a, AppContext>,
+    app: &'a mut AppContext,
     model_state: WeakModel<T>,
 }
 
 impl<'a, T: 'static> ModelContext<'a, T> {
-    pub(crate) fn mutable(app: &'a mut AppContext, model_state: WeakModel<T>) -> Self {
-        Self {
-            app: Reference::Mutable(app),
-            model_state,
-        }
+    pub(crate) fn new(app: &'a mut AppContext, model_state: WeakModel<T>) -> Self {
+        Self { app, model_state }
     }
 
     pub fn entity_id(&self) -> EntityId {
@@ -95,7 +93,7 @@ impl<'a, T: 'static> ModelContext<'a, T> {
 
     pub fn on_release(
         &mut self,
-        mut on_release: impl FnMut(&mut T, &mut AppContext) + 'static,
+        on_release: impl FnOnce(&mut T, &mut AppContext) + 'static,
     ) -> Subscription
     where
         T: 'static,
@@ -112,7 +110,7 @@ impl<'a, T: 'static> ModelContext<'a, T> {
     pub fn observe_release<T2, E>(
         &mut self,
         entity: &E,
-        mut on_release: impl FnMut(&mut T, &mut T2, &mut ModelContext<'_, T>) + 'static,
+        on_release: impl FnOnce(&mut T, &mut T2, &mut ModelContext<'_, T>) + 'static,
     ) -> Subscription
     where
         T: Any,
@@ -215,12 +213,11 @@ where
 }
 
 impl<'a, T> Context for ModelContext<'a, T> {
-    type ModelContext<'b, U> = ModelContext<'b, U>;
     type Result<U> = U;
 
     fn build_model<U: 'static>(
         &mut self,
-        build_model: impl FnOnce(&mut Self::ModelContext<'_, U>) -> U,
+        build_model: impl FnOnce(&mut ModelContext<'_, U>) -> U,
     ) -> Model<U> {
         self.app.build_model(build_model)
     }
@@ -228,10 +225,17 @@ impl<'a, T> Context for ModelContext<'a, T> {
     fn update_model<U: 'static, R>(
         &mut self,
         handle: &Model<U>,
-        update: impl FnOnce(&mut U, &mut Self::ModelContext<'_, U>) -> R,
+        update: impl FnOnce(&mut U, &mut ModelContext<'_, U>) -> R,
     ) -> R {
         self.app.update_model(handle, update)
     }
+
+    fn update_window<R, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<R>
+    where
+        F: FnOnce(AnyView, &mut WindowContext<'_>) -> R,
+    {
+        self.app.update_window(window, update)
+    }
 }
 
 impl<T> Borrow<AppContext> for ModelContext<'_, T> {
diff --git a/crates/gpui2/src/app/test_context.rs b/crates/gpui2/src/app/test_context.rs
index 6affabdd23..27275d3a04 100644
--- a/crates/gpui2/src/app/test_context.rs
+++ b/crates/gpui2/src/app/test_context.rs
@@ -1,7 +1,7 @@
 use crate::{
-    AnyWindowHandle, AppContext, AsyncAppContext, BackgroundExecutor, Context, EventEmitter,
-    ForegroundExecutor, Model, ModelContext, Result, Task, TestDispatcher, TestPlatform,
-    WindowContext,
+    AnyView, AnyWindowHandle, AppContext, AsyncAppContext, BackgroundExecutor, Context,
+    EventEmitter, ForegroundExecutor, Model, ModelContext, Result, Task, TestDispatcher,
+    TestPlatform, WindowContext,
 };
 use anyhow::{anyhow, bail};
 use futures::{Stream, StreamExt};
@@ -15,12 +15,11 @@ pub struct TestAppContext {
 }
 
 impl Context for TestAppContext {
-    type ModelContext<'a, T> = ModelContext<'a, T>;
     type Result<T> = T;
 
     fn build_model<T: 'static>(
         &mut self,
-        build_model: impl FnOnce(&mut Self::ModelContext<'_, T>) -> T,
+        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
     ) -> Self::Result<Model<T>>
     where
         T: 'static,
@@ -32,11 +31,19 @@ impl Context for TestAppContext {
     fn update_model<T: 'static, R>(
         &mut self,
         handle: &Model<T>,
-        update: impl FnOnce(&mut T, &mut Self::ModelContext<'_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
     ) -> Self::Result<R> {
         let mut app = self.app.borrow_mut();
         app.update_model(handle, update)
     }
+
+    fn update_window<T, F>(&mut self, window: AnyWindowHandle, f: F) -> Result<T>
+    where
+        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
+    {
+        let mut lock = self.app.borrow_mut();
+        lock.update_window(window, f)
+    }
 }
 
 impl TestAppContext {
@@ -80,22 +87,13 @@ impl TestAppContext {
         cx.update(f)
     }
 
-    pub fn read_window<R>(
-        &self,
-        handle: AnyWindowHandle,
-        read: impl FnOnce(&WindowContext) -> R,
-    ) -> R {
-        let app_context = self.app.borrow();
-        app_context.read_window(handle.id, read).unwrap()
-    }
-
     pub fn update_window<R>(
         &self,
         handle: AnyWindowHandle,
-        update: impl FnOnce(&mut WindowContext) -> R,
+        update: impl FnOnce(AnyView, &mut WindowContext) -> R,
     ) -> R {
         let mut app = self.app.borrow_mut();
-        app.update_window(handle.id, update).unwrap()
+        app.update_window(handle, update).unwrap()
     }
 
     pub fn spawn<Fut, R>(&self, f: impl FnOnce(AsyncAppContext) -> Fut) -> Task<R>
diff --git a/crates/gpui2/src/assets.rs b/crates/gpui2/src/assets.rs
index 39c8562b69..baf75b8aab 100644
--- a/crates/gpui2/src/assets.rs
+++ b/crates/gpui2/src/assets.rs
@@ -8,7 +8,7 @@ use std::{
     sync::atomic::{AtomicUsize, Ordering::SeqCst},
 };
 
-pub trait AssetSource: 'static + Send + Sync {
+pub trait AssetSource: 'static {
     fn load(&self, path: &str) -> Result<Cow<[u8]>>;
     fn list(&self, path: &str) -> Result<Vec<SharedString>>;
 }
diff --git a/crates/gpui2/src/element.rs b/crates/gpui2/src/element.rs
index e41dc4ebd5..4890b79a9a 100644
--- a/crates/gpui2/src/element.rs
+++ b/crates/gpui2/src/element.rs
@@ -219,7 +219,7 @@ impl<V, E, F> Element<V> for Option<F>
 where
     V: 'static,
     E: 'static + Component<V>,
-    F: FnOnce(&mut V, &mut ViewContext<'_, '_, V>) -> E + 'static,
+    F: FnOnce(&mut V, &mut ViewContext<'_, V>) -> E + 'static,
 {
     type ElementState = AnyElement<V>;
 
@@ -263,7 +263,7 @@ impl<V, E, F> Component<V> for Option<F>
 where
     V: 'static,
     E: 'static + Component<V>,
-    F: FnOnce(&mut V, &mut ViewContext<'_, '_, V>) -> E + 'static,
+    F: FnOnce(&mut V, &mut ViewContext<'_, V>) -> E + 'static,
 {
     fn render(self) -> AnyElement<V> {
         AnyElement::new(self)
@@ -274,7 +274,7 @@ impl<V, E, F> Component<V> for F
 where
     V: 'static,
     E: 'static + Component<V>,
-    F: FnOnce(&mut V, &mut ViewContext<'_, '_, V>) -> E + 'static,
+    F: FnOnce(&mut V, &mut ViewContext<'_, V>) -> E + 'static,
 {
     fn render(self) -> AnyElement<V> {
         AnyElement::new(Some(self))
diff --git a/crates/gpui2/src/elements/div.rs b/crates/gpui2/src/elements/div.rs
index 6fe10d94a3..56940efce4 100644
--- a/crates/gpui2/src/elements/div.rs
+++ b/crates/gpui2/src/elements/div.rs
@@ -305,7 +305,6 @@ where
 
 impl<V, I, F> Component<V> for Div<V, I, F>
 where
-    // V: Any + Send + Sync,
     I: ElementInteraction<V>,
     F: ElementFocus<V>,
 {
diff --git a/crates/gpui2/src/elements/text.rs b/crates/gpui2/src/elements/text.rs
index 3aff568c4c..4bc3705490 100644
--- a/crates/gpui2/src/elements/text.rs
+++ b/crates/gpui2/src/elements/text.rs
@@ -44,9 +44,6 @@ pub struct Text<V> {
     state_type: PhantomData<V>,
 }
 
-unsafe impl<V> Send for Text<V> {}
-unsafe impl<V> Sync for Text<V> {}
-
 impl<V: 'static> Component<V> for Text<V> {
     fn render(self) -> AnyElement<V> {
         AnyElement::new(self)
diff --git a/crates/gpui2/src/focusable.rs b/crates/gpui2/src/focusable.rs
index d7cfc5fe8f..99f8bb1dd6 100644
--- a/crates/gpui2/src/focusable.rs
+++ b/crates/gpui2/src/focusable.rs
@@ -8,7 +8,7 @@ use smallvec::SmallVec;
 pub type FocusListeners<V> = SmallVec<[FocusListener<V>; 2]>;
 
 pub type FocusListener<V> =
-    Box<dyn Fn(&mut V, &FocusHandle, &FocusEvent, &mut ViewContext<V>) + Send + 'static>;
+    Box<dyn Fn(&mut V, &FocusHandle, &FocusEvent, &mut ViewContext<V>) + 'static>;
 
 pub trait Focusable<V: 'static>: Element<V> {
     fn focus_listeners(&mut self) -> &mut FocusListeners<V>;
@@ -42,7 +42,7 @@ pub trait Focusable<V: 'static>: Element<V> {
 
     fn on_focus(
         mut self,
-        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + Send + 'static,
+        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + 'static,
     ) -> Self
     where
         Self: Sized,
@@ -58,7 +58,7 @@ pub trait Focusable<V: 'static>: Element<V> {
 
     fn on_blur(
         mut self,
-        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + Send + 'static,
+        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + 'static,
     ) -> Self
     where
         Self: Sized,
@@ -74,7 +74,7 @@ pub trait Focusable<V: 'static>: Element<V> {
 
     fn on_focus_in(
         mut self,
-        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + Send + 'static,
+        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + 'static,
     ) -> Self
     where
         Self: Sized,
@@ -99,7 +99,7 @@ pub trait Focusable<V: 'static>: Element<V> {
 
     fn on_focus_out(
         mut self,
-        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + Send + 'static,
+        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + 'static,
     ) -> Self
     where
         Self: Sized,
@@ -122,7 +122,7 @@ pub trait Focusable<V: 'static>: Element<V> {
     }
 }
 
-pub trait ElementFocus<V: 'static>: 'static + Send {
+pub trait ElementFocus<V: 'static>: 'static {
     fn as_focusable(&self) -> Option<&FocusEnabled<V>>;
     fn as_focusable_mut(&mut self) -> Option<&mut FocusEnabled<V>>;
 
diff --git a/crates/gpui2/src/geometry.rs b/crates/gpui2/src/geometry.rs
index eedf8bbb2c..7d4073144c 100644
--- a/crates/gpui2/src/geometry.rs
+++ b/crates/gpui2/src/geometry.rs
@@ -931,6 +931,18 @@ impl From<f64> for GlobalPixels {
     }
 }
 
+impl sqlez::bindable::StaticColumnCount for GlobalPixels {}
+
+impl sqlez::bindable::Bind for GlobalPixels {
+    fn bind(
+        &self,
+        statement: &sqlez::statement::Statement,
+        start_index: i32,
+    ) -> anyhow::Result<i32> {
+        self.0.bind(statement, start_index)
+    }
+}
+
 #[derive(Clone, Copy, Default, Add, Sub, Mul, Div, Neg)]
 pub struct Rems(f32);
 
diff --git a/crates/gpui2/src/gpui2.rs b/crates/gpui2/src/gpui2.rs
index 755df91b93..49cc3cebc2 100644
--- a/crates/gpui2/src/gpui2.rs
+++ b/crates/gpui2/src/gpui2.rs
@@ -68,34 +68,36 @@ use derive_more::{Deref, DerefMut};
 use std::{
     any::{Any, TypeId},
     borrow::{Borrow, BorrowMut},
-    ops::{Deref, DerefMut},
 };
 use taffy::TaffyLayoutEngine;
 
 type AnyBox = Box<dyn Any>;
 
 pub trait Context {
-    type ModelContext<'a, T>;
     type Result<T>;
 
     fn build_model<T: 'static>(
         &mut self,
-        build_model: impl FnOnce(&mut Self::ModelContext<'_, T>) -> T,
+        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
     ) -> Self::Result<Model<T>>;
 
-    fn update_model<T: 'static, R>(
+    fn update_model<T, R>(
         &mut self,
         handle: &Model<T>,
-        update: impl FnOnce(&mut T, &mut Self::ModelContext<'_, T>) -> R,
-    ) -> Self::Result<R>;
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
+    ) -> Self::Result<R>
+    where
+        T: 'static;
+
+    fn update_window<T, F>(&mut self, window: AnyWindowHandle, f: F) -> Result<T>
+    where
+        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T;
 }
 
 pub trait VisualContext: Context {
-    type ViewContext<'a, 'w, V>;
-
     fn build_view<V>(
         &mut self,
-        build_view_state: impl FnOnce(&mut Self::ViewContext<'_, '_, V>) -> V,
+        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
     ) -> Self::Result<View<V>>
     where
         V: 'static;
@@ -103,12 +105,19 @@ pub trait VisualContext: Context {
     fn update_view<V: 'static, R>(
         &mut self,
         view: &View<V>,
-        update: impl FnOnce(&mut V, &mut Self::ViewContext<'_, '_, V>) -> R,
+        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
     ) -> Self::Result<R>;
+
+    fn replace_root_view<V>(
+        &mut self,
+        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
+    ) -> Self::Result<View<V>>
+    where
+        V: Render;
 }
 
 pub trait Entity<T>: Sealed {
-    type Weak: 'static + Send;
+    type Weak: 'static;
 
     fn entity_id(&self) -> EntityId;
     fn downgrade(&self) -> Self::Weak;
@@ -128,7 +137,7 @@ pub trait BorrowAppContext {
     where
         F: FnOnce(&mut Self) -> R;
 
-    fn set_global<T: Send + 'static>(&mut self, global: T);
+    fn set_global<T: 'static>(&mut self, global: T);
 }
 
 impl<C> BorrowAppContext for C
@@ -145,7 +154,7 @@ where
         result
     }
 
-    fn set_global<G: 'static + Send>(&mut self, global: G) {
+    fn set_global<G: 'static>(&mut self, global: G) {
         self.borrow_mut().set_global(global)
     }
 }
@@ -208,30 +217,3 @@ impl<T: Into<ArcCow<'static, str>>> From<T> for SharedString {
         Self(value.into())
     }
 }
-
-pub enum Reference<'a, T> {
-    Immutable(&'a T),
-    Mutable(&'a mut T),
-}
-
-impl<'a, T> Deref for Reference<'a, T> {
-    type Target = T;
-
-    fn deref(&self) -> &Self::Target {
-        match self {
-            Reference::Immutable(target) => target,
-            Reference::Mutable(target) => target,
-        }
-    }
-}
-
-impl<'a, T> DerefMut for Reference<'a, T> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        match self {
-            Reference::Immutable(_) => {
-                panic!("cannot mutably deref an immutable reference. this is a bug in GPUI.");
-            }
-            Reference::Mutable(target) => target,
-        }
-    }
-}
diff --git a/crates/gpui2/src/platform.rs b/crates/gpui2/src/platform.rs
index 705c2f83bb..2dd4d8b666 100644
--- a/crates/gpui2/src/platform.rs
+++ b/crates/gpui2/src/platform.rs
@@ -9,12 +9,14 @@ use crate::{
     ForegroundExecutor, GlobalPixels, GlyphId, InputEvent, LineLayout, Pixels, Point,
     RenderGlyphParams, RenderImageParams, RenderSvgParams, Result, Scene, SharedString, Size,
 };
-use anyhow::anyhow;
+use anyhow::{anyhow, bail};
 use async_task::Runnable;
 use futures::channel::oneshot;
 use parking::Unparker;
 use seahash::SeaHasher;
 use serde::{Deserialize, Serialize};
+use sqlez::bindable::{Bind, Column, StaticColumnCount};
+use sqlez::statement::Statement;
 use std::borrow::Cow;
 use std::hash::{Hash, Hasher};
 use std::time::Duration;
@@ -27,6 +29,7 @@ use std::{
     str::FromStr,
     sync::Arc,
 };
+use uuid::Uuid;
 
 pub use keystroke::*;
 #[cfg(target_os = "macos")]
@@ -106,6 +109,9 @@ pub(crate) trait Platform: 'static {
 
 pub trait PlatformDisplay: Send + Sync + Debug {
     fn id(&self) -> DisplayId;
+    /// Returns a stable identifier for this display that can be persisted and used
+    /// across system restarts.
+    fn uuid(&self) -> Result<Uuid>;
     fn as_any(&self) -> &dyn Any;
     fn bounds(&self) -> Bounds<GlobalPixels>;
 }
@@ -372,6 +378,64 @@ pub enum WindowBounds {
     Fixed(Bounds<GlobalPixels>),
 }
 
+impl StaticColumnCount for WindowBounds {
+    fn column_count() -> usize {
+        5
+    }
+}
+
+impl Bind for WindowBounds {
+    fn bind(&self, statement: &Statement, start_index: i32) -> Result<i32> {
+        let (region, next_index) = match self {
+            WindowBounds::Fullscreen => {
+                let next_index = statement.bind(&"Fullscreen", start_index)?;
+                (None, next_index)
+            }
+            WindowBounds::Maximized => {
+                let next_index = statement.bind(&"Maximized", start_index)?;
+                (None, next_index)
+            }
+            WindowBounds::Fixed(region) => {
+                let next_index = statement.bind(&"Fixed", start_index)?;
+                (Some(*region), next_index)
+            }
+        };
+
+        statement.bind(
+            &region.map(|region| {
+                (
+                    region.origin.x,
+                    region.origin.y,
+                    region.size.width,
+                    region.size.height,
+                )
+            }),
+            next_index,
+        )
+    }
+}
+
+impl Column for WindowBounds {
+    fn column(statement: &mut Statement, start_index: i32) -> Result<(Self, i32)> {
+        let (window_state, next_index) = String::column(statement, start_index)?;
+        let bounds = match window_state.as_str() {
+            "Fullscreen" => WindowBounds::Fullscreen,
+            "Maximized" => WindowBounds::Maximized,
+            "Fixed" => {
+                // let ((x, y, width, height), _) = Column::column(statement, next_index)?;
+                // WindowBounds::Fixed(RectF::new(
+                //     Vector2F::new(x, y),
+                //     Vector2F::new(width, height),
+                // ))
+                todo!()
+            }
+            _ => bail!("Window State did not have a valid string"),
+        };
+
+        Ok((bounds, next_index + 4))
+    }
+}
+
 #[derive(Copy, Clone, Debug)]
 pub enum WindowAppearance {
     Light,
diff --git a/crates/gpui2/src/platform/mac/display.rs b/crates/gpui2/src/platform/mac/display.rs
index dc064293f3..b326eaa66d 100644
--- a/crates/gpui2/src/platform/mac/display.rs
+++ b/crates/gpui2/src/platform/mac/display.rs
@@ -1,9 +1,12 @@
 use crate::{point, size, Bounds, DisplayId, GlobalPixels, PlatformDisplay};
+use anyhow::Result;
+use core_foundation::uuid::{CFUUIDGetUUIDBytes, CFUUIDRef};
 use core_graphics::{
     display::{CGDirectDisplayID, CGDisplayBounds, CGGetActiveDisplayList},
     geometry::{CGPoint, CGRect, CGSize},
 };
 use std::any::Any;
+use uuid::Uuid;
 
 #[derive(Debug)]
 pub struct MacDisplay(pub(crate) CGDirectDisplayID);
@@ -11,17 +14,23 @@ pub struct MacDisplay(pub(crate) CGDirectDisplayID);
 unsafe impl Send for MacDisplay {}
 
 impl MacDisplay {
-    /// Get the screen with the given UUID.
+    /// Get the screen with the given [DisplayId].
     pub fn find_by_id(id: DisplayId) -> Option<Self> {
         Self::all().find(|screen| screen.id() == id)
     }
 
+    /// Get the screen with the given persistent [Uuid].
+    pub fn find_by_uuid(uuid: Uuid) -> Option<Self> {
+        Self::all().find(|screen| screen.uuid().ok() == Some(uuid))
+    }
+
     /// Get the primary screen - the one with the menu bar, and whose bottom left
     /// corner is at the origin of the AppKit coordinate system.
     pub fn primary() -> Self {
         Self::all().next().unwrap()
     }
 
+    /// Obtains an iterator over all currently active system displays.
     pub fn all() -> impl Iterator<Item = Self> {
         unsafe {
             let mut display_count: u32 = 0;
@@ -40,6 +49,11 @@ impl MacDisplay {
     }
 }
 
+#[link(name = "ApplicationServices", kind = "framework")]
+extern "C" {
+    pub fn CGDisplayCreateUUIDFromDisplayID(display: CGDirectDisplayID) -> CFUUIDRef;
+}
+
 /// Convert the given rectangle from CoreGraphics' native coordinate space to GPUI's coordinate space.
 ///
 /// CoreGraphics' coordinate space has its origin at the bottom left of the primary screen,
@@ -88,6 +102,34 @@ impl PlatformDisplay for MacDisplay {
         DisplayId(self.0)
     }
 
+    fn uuid(&self) -> Result<Uuid> {
+        let cfuuid = unsafe { CGDisplayCreateUUIDFromDisplayID(self.0 as CGDirectDisplayID) };
+        anyhow::ensure!(
+            !cfuuid.is_null(),
+            "AppKit returned a null from CGDisplayCreateUUIDFromDisplayID"
+        );
+
+        let bytes = unsafe { CFUUIDGetUUIDBytes(cfuuid) };
+        Ok(Uuid::from_bytes([
+            bytes.byte0,
+            bytes.byte1,
+            bytes.byte2,
+            bytes.byte3,
+            bytes.byte4,
+            bytes.byte5,
+            bytes.byte6,
+            bytes.byte7,
+            bytes.byte8,
+            bytes.byte9,
+            bytes.byte10,
+            bytes.byte11,
+            bytes.byte12,
+            bytes.byte13,
+            bytes.byte14,
+            bytes.byte15,
+        ]))
+    }
+
     fn as_any(&self) -> &dyn Any {
         self
     }
diff --git a/crates/gpui2/src/view.rs b/crates/gpui2/src/view.rs
index 06b20a3088..3cc4fdd4e3 100644
--- a/crates/gpui2/src/view.rs
+++ b/crates/gpui2/src/view.rs
@@ -1,12 +1,12 @@
 use crate::{
     private::Sealed, AnyBox, AnyElement, AnyModel, AnyWeakModel, AppContext, AvailableSpace,
-    BorrowWindow, Bounds, Component, Element, ElementId, Entity, EntityId, LayoutId, Model, Pixels,
-    Size, ViewContext, VisualContext, WeakModel, WindowContext,
+    BorrowWindow, Bounds, Component, Element, ElementId, Entity, EntityId, Flatten, LayoutId,
+    Model, Pixels, Size, ViewContext, VisualContext, WeakModel, WindowContext,
 };
 use anyhow::{Context, Result};
 use std::{
     any::{Any, TypeId},
-    marker::PhantomData,
+    hash::{Hash, Hasher},
 };
 
 pub trait Render: 'static + Sized {
@@ -52,7 +52,7 @@ impl<V: 'static> View<V> {
     pub fn update<C, R>(
         &self,
         cx: &mut C,
-        f: impl FnOnce(&mut V, &mut C::ViewContext<'_, '_, V>) -> R,
+        f: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
     ) -> C::Result<R>
     where
         C: VisualContext,
@@ -73,55 +73,23 @@ impl<V> Clone for View<V> {
     }
 }
 
-impl<V: Render, ParentViewState: 'static> Component<ParentViewState> for View<V> {
-    fn render(self) -> AnyElement<ParentViewState> {
-        AnyElement::new(EraseViewState {
-            view: self,
-            parent_view_state_type: PhantomData,
-        })
+impl<V> Hash for View<V> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.model.hash(state);
     }
 }
 
-impl<V> Element<()> for View<V>
-where
-    V: Render,
-{
-    type ElementState = AnyElement<V>;
-
-    fn id(&self) -> Option<crate::ElementId> {
-        Some(ElementId::View(self.model.entity_id))
+impl<V> PartialEq for View<V> {
+    fn eq(&self, other: &Self) -> bool {
+        self.model == other.model
     }
+}
 
-    fn initialize(
-        &mut self,
-        _: &mut (),
-        _: Option<Self::ElementState>,
-        cx: &mut ViewContext<()>,
-    ) -> Self::ElementState {
-        self.update(cx, |state, cx| {
-            let mut any_element = AnyElement::new(state.render(cx));
-            any_element.initialize(state, cx);
-            any_element
-        })
-    }
+impl<V> Eq for View<V> {}
 
-    fn layout(
-        &mut self,
-        _: &mut (),
-        element: &mut Self::ElementState,
-        cx: &mut ViewContext<()>,
-    ) -> LayoutId {
-        self.update(cx, |state, cx| element.layout(state, cx))
-    }
-
-    fn paint(
-        &mut self,
-        _: Bounds<Pixels>,
-        _: &mut (),
-        element: &mut Self::ElementState,
-        cx: &mut ViewContext<()>,
-    ) {
-        self.update(cx, |state, cx| element.paint(state, cx))
+impl<V: Render, ParentViewState: 'static> Component<ParentViewState> for View<V> {
+    fn render(self) -> AnyElement<ParentViewState> {
+        AnyElement::new(AnyView::from(self))
     }
 }
 
@@ -134,13 +102,17 @@ impl<V: 'static> WeakView<V> {
         Entity::upgrade_from(self)
     }
 
-    pub fn update<R>(
+    pub fn update<C, R>(
         &self,
-        cx: &mut WindowContext,
-        f: impl FnOnce(&mut V, &mut ViewContext<V>) -> R,
-    ) -> Result<R> {
+        cx: &mut C,
+        f: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
+    ) -> Result<R>
+    where
+        C: VisualContext,
+        Result<C::Result<R>>: Flatten<R>,
+    {
         let view = self.upgrade().context("error upgrading view")?;
-        Ok(view.update(cx, f))
+        Ok(view.update(cx, f)).flatten()
     }
 }
 
@@ -152,115 +124,19 @@ impl<V> Clone for WeakView<V> {
     }
 }
 
-struct EraseViewState<V, ParentV> {
-    view: View<V>,
-    parent_view_state_type: PhantomData<ParentV>,
-}
-
-unsafe impl<V, ParentV> Send for EraseViewState<V, ParentV> {}
-
-impl<V: Render, ParentV: 'static> Component<ParentV> for EraseViewState<V, ParentV> {
-    fn render(self) -> AnyElement<ParentV> {
-        AnyElement::new(self)
+impl<V> Hash for WeakView<V> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.model.hash(state);
     }
 }
 
-impl<V: Render, ParentV: 'static> Element<ParentV> for EraseViewState<V, ParentV> {
-    type ElementState = Box<dyn Any>;
-
-    fn id(&self) -> Option<crate::ElementId> {
-        Element::id(&self.view)
-    }
-
-    fn initialize(
-        &mut self,
-        _: &mut ParentV,
-        _: Option<Self::ElementState>,
-        cx: &mut ViewContext<ParentV>,
-    ) -> Self::ElementState {
-        ViewObject::initialize(&mut self.view, cx)
-    }
-
-    fn layout(
-        &mut self,
-        _: &mut ParentV,
-        element: &mut Self::ElementState,
-        cx: &mut ViewContext<ParentV>,
-    ) -> LayoutId {
-        ViewObject::layout(&mut self.view, element, cx)
-    }
-
-    fn paint(
-        &mut self,
-        bounds: Bounds<Pixels>,
-        _: &mut ParentV,
-        element: &mut Self::ElementState,
-        cx: &mut ViewContext<ParentV>,
-    ) {
-        ViewObject::paint(&mut self.view, bounds, element, cx)
+impl<V> PartialEq for WeakView<V> {
+    fn eq(&self, other: &Self) -> bool {
+        self.model == other.model
     }
 }
 
-trait ViewObject: Send + Sync {
-    fn entity_type(&self) -> TypeId;
-    fn entity_id(&self) -> EntityId;
-    fn model(&self) -> AnyModel;
-    fn initialize(&self, cx: &mut WindowContext) -> AnyBox;
-    fn layout(&self, element: &mut AnyBox, cx: &mut WindowContext) -> LayoutId;
-    fn paint(&self, bounds: Bounds<Pixels>, element: &mut AnyBox, cx: &mut WindowContext);
-    fn debug(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result;
-}
-
-impl<V> ViewObject for View<V>
-where
-    V: Render,
-{
-    fn entity_type(&self) -> TypeId {
-        TypeId::of::<V>()
-    }
-
-    fn entity_id(&self) -> EntityId {
-        Entity::entity_id(self)
-    }
-
-    fn model(&self) -> AnyModel {
-        self.model.clone().into_any()
-    }
-
-    fn initialize(&self, cx: &mut WindowContext) -> AnyBox {
-        cx.with_element_id(ViewObject::entity_id(self), |_global_id, cx| {
-            self.update(cx, |state, cx| {
-                let mut any_element = Box::new(AnyElement::new(state.render(cx)));
-                any_element.initialize(state, cx);
-                any_element
-            })
-        })
-    }
-
-    fn layout(&self, element: &mut AnyBox, cx: &mut WindowContext) -> LayoutId {
-        cx.with_element_id(ViewObject::entity_id(self), |_global_id, cx| {
-            self.update(cx, |state, cx| {
-                let element = element.downcast_mut::<AnyElement<V>>().unwrap();
-                element.layout(state, cx)
-            })
-        })
-    }
-
-    fn paint(&self, _: Bounds<Pixels>, element: &mut AnyBox, cx: &mut WindowContext) {
-        cx.with_element_id(ViewObject::entity_id(self), |_global_id, cx| {
-            self.update(cx, |state, cx| {
-                let element = element.downcast_mut::<AnyElement<V>>().unwrap();
-                element.paint(state, cx);
-            });
-        });
-    }
-
-    fn debug(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct(&format!("AnyView<{}>", std::any::type_name::<V>()))
-            .field("entity_id", &ViewObject::entity_id(self).as_u64())
-            .finish()
-    }
-}
+impl<V> Eq for WeakView<V> {}
 
 #[derive(Clone, Debug)]
 pub struct AnyView {
@@ -292,7 +168,7 @@ impl AnyView {
         }
     }
 
-    pub(crate) fn entity_type(&self) -> TypeId {
+    pub fn entity_type(&self) -> TypeId {
         self.model.entity_type
     }
 
diff --git a/crates/gpui2/src/window.rs b/crates/gpui2/src/window.rs
index e7cfcf45ee..5f2de2e428 100644
--- a/crates/gpui2/src/window.rs
+++ b/crates/gpui2/src/window.rs
@@ -5,11 +5,11 @@ use crate::{
     Hsla, ImageData, InputEvent, IsZero, KeyListener, KeyMatch, KeyMatcher, Keystroke, LayoutId,
     Model, ModelContext, Modifiers, MonochromeSprite, MouseButton, MouseDownEvent, MouseMoveEvent,
     MouseUpEvent, Path, Pixels, PlatformAtlas, PlatformWindow, Point, PolychromeSprite, Quad,
-    Reference, RenderGlyphParams, RenderImageParams, RenderSvgParams, ScaledPixels, SceneBuilder,
+    Render, RenderGlyphParams, RenderImageParams, RenderSvgParams, ScaledPixels, SceneBuilder,
     Shadow, SharedString, Size, Style, Subscription, TaffyLayoutEngine, Task, Underline,
-    UnderlineStyle, View, VisualContext, WeakModel, WeakView, WindowOptions, SUBPIXEL_VARIANTS,
+    UnderlineStyle, View, VisualContext, WeakView, WindowOptions, SUBPIXEL_VARIANTS,
 };
-use anyhow::Result;
+use anyhow::{anyhow, Result};
 use collections::HashMap;
 use derive_more::{Deref, DerefMut};
 use parking_lot::RwLock;
@@ -20,6 +20,7 @@ use std::{
     borrow::{Borrow, BorrowMut, Cow},
     fmt::Debug,
     future::Future,
+    hash::{Hash, Hasher},
     marker::PhantomData,
     mem,
     sync::{
@@ -156,7 +157,7 @@ impl Drop for FocusHandle {
 
 // Holds the state for a specific window.
 pub struct Window {
-    handle: AnyWindowHandle,
+    pub(crate) handle: AnyWindowHandle,
     platform_window: Box<dyn PlatformWindow>,
     display_id: DisplayId,
     sprite_atlas: Arc<dyn PlatformAtlas>,
@@ -201,23 +202,25 @@ impl Window {
         let content_size = platform_window.content_size();
         let scale_factor = platform_window.scale_factor();
         platform_window.on_resize(Box::new({
-            let cx = cx.to_async();
+            let mut cx = cx.to_async();
             move |content_size, scale_factor| {
-                cx.update_window(handle, |cx| {
-                    cx.window.scale_factor = scale_factor;
-                    cx.window.scene_builder = SceneBuilder::new();
-                    cx.window.content_size = content_size;
-                    cx.window.display_id = cx.window.platform_window.display().id();
-                    cx.window.dirty = true;
-                })
-                .log_err();
+                handle
+                    .update(&mut cx, |_, cx| {
+                        cx.window.scale_factor = scale_factor;
+                        cx.window.scene_builder = SceneBuilder::new();
+                        cx.window.content_size = content_size;
+                        cx.window.display_id = cx.window.platform_window.display().id();
+                        cx.window.dirty = true;
+                    })
+                    .log_err();
             }
         }));
 
         platform_window.on_input({
-            let cx = cx.to_async();
+            let mut cx = cx.to_async();
             Box::new(move |event| {
-                cx.update_window(handle, |cx| cx.dispatch_event(event))
+                handle
+                    .update(&mut cx, |_, cx| cx.dispatch_event(event))
                     .log_err()
                     .unwrap_or(true)
             })
@@ -296,24 +299,14 @@ impl ContentMask<Pixels> {
 /// Provides access to application state in the context of a single window. Derefs
 /// to an `AppContext`, so you can also pass a `WindowContext` to any method that takes
 /// an `AppContext` and call any `AppContext` methods.
-pub struct WindowContext<'a, 'w> {
-    pub(crate) app: Reference<'a, AppContext>,
-    pub(crate) window: Reference<'w, Window>,
+pub struct WindowContext<'a> {
+    pub(crate) app: &'a mut AppContext,
+    pub(crate) window: &'a mut Window,
 }
 
-impl<'a, 'w> WindowContext<'a, 'w> {
-    pub(crate) fn immutable(app: &'a AppContext, window: &'w Window) -> Self {
-        Self {
-            app: Reference::Immutable(app),
-            window: Reference::Immutable(window),
-        }
-    }
-
-    pub(crate) fn mutable(app: &'a mut AppContext, window: &'w mut Window) -> Self {
-        Self {
-            app: Reference::Mutable(app),
-            window: Reference::Mutable(window),
-        }
+impl<'a> WindowContext<'a> {
+    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window) -> Self {
+        Self { app, window }
     }
 
     /// Obtain a handle to the window that belongs to this context.
@@ -345,10 +338,9 @@ impl<'a, 'w> WindowContext<'a, 'w> {
             self.window.last_blur = Some(self.window.focus);
         }
 
-        let window_id = self.window.handle.id;
         self.window.focus = Some(handle.id);
         self.app.push_effect(Effect::FocusChanged {
-            window_id,
+            window_handle: self.window.handle,
             focused: Some(handle.id),
         });
         self.notify();
@@ -360,15 +352,53 @@ impl<'a, 'w> WindowContext<'a, 'w> {
             self.window.last_blur = Some(self.window.focus);
         }
 
-        let window_id = self.window.handle.id;
         self.window.focus = None;
         self.app.push_effect(Effect::FocusChanged {
-            window_id,
+            window_handle: self.window.handle,
             focused: None,
         });
         self.notify();
     }
 
+    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
+    /// that are currently on the stack to be returned to the app.
+    pub fn defer(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
+        let handle = self.window.handle;
+        self.app.defer(move |cx| {
+            handle.update(cx, |_, cx| f(cx)).ok();
+        });
+    }
+
+    pub fn subscribe<Emitter, E>(
+        &mut self,
+        entity: &E,
+        mut on_event: impl FnMut(E, &Emitter::Event, &mut WindowContext<'_>) + 'static,
+    ) -> Subscription
+    where
+        Emitter: EventEmitter,
+        E: Entity<Emitter>,
+    {
+        let entity_id = entity.entity_id();
+        let entity = entity.downgrade();
+        let window_handle = self.window.handle;
+        self.app.event_listeners.insert(
+            entity_id,
+            Box::new(move |event, cx| {
+                window_handle
+                    .update(cx, |_, cx| {
+                        if let Some(handle) = E::upgrade_from(&entity) {
+                            let event = event.downcast_ref().expect("invalid event type");
+                            on_event(handle, event, cx);
+                            true
+                        } else {
+                            false
+                        }
+                    })
+                    .unwrap_or(false)
+            }),
+        )
+    }
+
     /// Create an `AsyncWindowContext`, which has a static lifetime and can be held across
     /// await points in async code.
     pub fn to_async(&self) -> AsyncWindowContext {
@@ -376,7 +406,7 @@ impl<'a, 'w> WindowContext<'a, 'w> {
     }
 
     /// Schedule the given closure to be run directly after the current frame is rendered.
-    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut WindowContext) + Send + 'static) {
+    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut WindowContext) + 'static) {
         let f = Box::new(f);
         let display_id = self.window.display_id;
 
@@ -387,12 +417,12 @@ impl<'a, 'w> WindowContext<'a, 'w> {
                 return;
             }
         } else {
-            let async_cx = self.to_async();
+            let mut async_cx = self.to_async();
             self.next_frame_callbacks.insert(display_id, vec![f]);
             self.platform().set_display_link_output_callback(
                 display_id,
                 Box::new(move |_current_time, _output_time| {
-                    let _ = async_cx.update(|cx| {
+                    let _ = async_cx.update(|_, cx| {
                         let callbacks = cx
                             .next_frame_callbacks
                             .get_mut(&display_id)
@@ -1114,12 +1144,12 @@ impl<'a, 'w> WindowContext<'a, 'w> {
     /// is updated.
     pub fn observe_global<G: 'static>(
         &mut self,
-        f: impl Fn(&mut WindowContext<'_, '_>) + Send + 'static,
+        f: impl Fn(&mut WindowContext<'_>) + 'static,
     ) -> Subscription {
-        let window_id = self.window.handle.id;
+        let window_handle = self.window.handle;
         self.global_observers.insert(
             TypeId::of::<G>(),
-            Box::new(move |cx| cx.update_window(window_id, |cx| f(cx)).is_ok()),
+            Box::new(move |cx| window_handle.update(cx, |_, cx| f(cx)).is_ok()),
         )
     }
 
@@ -1202,43 +1232,52 @@ impl<'a, 'w> WindowContext<'a, 'w> {
     }
 }
 
-impl Context for WindowContext<'_, '_> {
-    type ModelContext<'a, T> = ModelContext<'a, T>;
+impl Context for WindowContext<'_> {
     type Result<T> = T;
 
     fn build_model<T>(
         &mut self,
-        build_model: impl FnOnce(&mut Self::ModelContext<'_, T>) -> T,
+        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
     ) -> Model<T>
     where
         T: 'static,
     {
         let slot = self.app.entities.reserve();
-        let model = build_model(&mut ModelContext::mutable(&mut *self.app, slot.downgrade()));
+        let model = build_model(&mut ModelContext::new(&mut *self.app, slot.downgrade()));
         self.entities.insert(slot, model)
     }
 
     fn update_model<T: 'static, R>(
         &mut self,
         model: &Model<T>,
-        update: impl FnOnce(&mut T, &mut Self::ModelContext<'_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
     ) -> R {
         let mut entity = self.entities.lease(model);
         let result = update(
             &mut *entity,
-            &mut ModelContext::mutable(&mut *self.app, model.downgrade()),
+            &mut ModelContext::new(&mut *self.app, model.downgrade()),
         );
         self.entities.end_lease(entity);
         result
     }
+
+    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
+    where
+        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
+    {
+        if window == self.window.handle {
+            let root_view = self.window.root_view.clone().unwrap();
+            Ok(update(root_view, self))
+        } else {
+            window.update(self.app, update)
+        }
+    }
 }
 
-impl VisualContext for WindowContext<'_, '_> {
-    type ViewContext<'a, 'w, V> = ViewContext<'a, 'w, V>;
-
+impl VisualContext for WindowContext<'_> {
     fn build_view<V>(
         &mut self,
-        build_view_state: impl FnOnce(&mut Self::ViewContext<'_, '_, V>) -> V,
+        build_view_state: impl FnOnce(&mut ViewContext<'_, V>) -> V,
     ) -> Self::Result<View<V>>
     where
         V: 'static,
@@ -1247,7 +1286,7 @@ impl VisualContext for WindowContext<'_, '_> {
         let view = View {
             model: slot.clone(),
         };
-        let mut cx = ViewContext::mutable(&mut *self.app, &mut *self.window, view.downgrade());
+        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
         let entity = build_view_state(&mut cx);
         self.entities.insert(slot, entity);
         view
@@ -1257,17 +1296,35 @@ impl VisualContext for WindowContext<'_, '_> {
     fn update_view<T: 'static, R>(
         &mut self,
         view: &View<T>,
-        update: impl FnOnce(&mut T, &mut Self::ViewContext<'_, '_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ViewContext<'_, T>) -> R,
     ) -> Self::Result<R> {
         let mut lease = self.app.entities.lease(&view.model);
-        let mut cx = ViewContext::mutable(&mut *self.app, &mut *self.window, view.downgrade());
+        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
         let result = update(&mut *lease, &mut cx);
         cx.app.entities.end_lease(lease);
         result
     }
+
+    fn replace_root_view<V>(
+        &mut self,
+        build_view: impl FnOnce(&mut ViewContext<'_, V>) -> V,
+    ) -> Self::Result<View<V>>
+    where
+        V: Render,
+    {
+        let slot = self.app.entities.reserve();
+        let view = View {
+            model: slot.clone(),
+        };
+        let mut cx = ViewContext::new(&mut *self.app, &mut *self.window, &view);
+        let entity = build_view(&mut cx);
+        self.entities.insert(slot, entity);
+        self.window.root_view = Some(view.clone().into());
+        view
+    }
 }
 
-impl<'a, 'w> std::ops::Deref for WindowContext<'a, 'w> {
+impl<'a> std::ops::Deref for WindowContext<'a> {
     type Target = AppContext;
 
     fn deref(&self) -> &Self::Target {
@@ -1275,19 +1332,19 @@ impl<'a, 'w> std::ops::Deref for WindowContext<'a, 'w> {
     }
 }
 
-impl<'a, 'w> std::ops::DerefMut for WindowContext<'a, 'w> {
+impl<'a> std::ops::DerefMut for WindowContext<'a> {
     fn deref_mut(&mut self) -> &mut Self::Target {
         &mut self.app
     }
 }
 
-impl<'a, 'w> Borrow<AppContext> for WindowContext<'a, 'w> {
+impl<'a> Borrow<AppContext> for WindowContext<'a> {
     fn borrow(&self) -> &AppContext {
         &self.app
     }
 }
 
-impl<'a, 'w> BorrowMut<AppContext> for WindowContext<'a, 'w> {
+impl<'a> BorrowMut<AppContext> for WindowContext<'a> {
     fn borrow_mut(&mut self) -> &mut AppContext {
         &mut self.app
     }
@@ -1455,13 +1512,13 @@ pub trait BorrowWindow: BorrowMut<Window> + BorrowMut<AppContext> {
     }
 }
 
-impl Borrow<Window> for WindowContext<'_, '_> {
+impl Borrow<Window> for WindowContext<'_> {
     fn borrow(&self) -> &Window {
         &self.window
     }
 }
 
-impl BorrowMut<Window> for WindowContext<'_, '_> {
+impl BorrowMut<Window> for WindowContext<'_> {
     fn borrow_mut(&mut self) -> &mut Window {
         &mut self.window
     }
@@ -1469,52 +1526,48 @@ impl BorrowMut<Window> for WindowContext<'_, '_> {
 
 impl<T> BorrowWindow for T where T: BorrowMut<AppContext> + BorrowMut<Window> {}
 
-pub struct ViewContext<'a, 'w, V> {
-    window_cx: WindowContext<'a, 'w>,
-    view: WeakView<V>,
+pub struct ViewContext<'a, V> {
+    window_cx: WindowContext<'a>,
+    view: &'a View<V>,
 }
 
-impl<V> Borrow<AppContext> for ViewContext<'_, '_, V> {
+impl<V> Borrow<AppContext> for ViewContext<'_, V> {
     fn borrow(&self) -> &AppContext {
         &*self.window_cx.app
     }
 }
 
-impl<V> BorrowMut<AppContext> for ViewContext<'_, '_, V> {
+impl<V> BorrowMut<AppContext> for ViewContext<'_, V> {
     fn borrow_mut(&mut self) -> &mut AppContext {
         &mut *self.window_cx.app
     }
 }
 
-impl<V> Borrow<Window> for ViewContext<'_, '_, V> {
+impl<V> Borrow<Window> for ViewContext<'_, V> {
     fn borrow(&self) -> &Window {
         &*self.window_cx.window
     }
 }
 
-impl<V> BorrowMut<Window> for ViewContext<'_, '_, V> {
+impl<V> BorrowMut<Window> for ViewContext<'_, V> {
     fn borrow_mut(&mut self) -> &mut Window {
         &mut *self.window_cx.window
     }
 }
 
-impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
-    pub(crate) fn mutable(
-        app: &'a mut AppContext,
-        window: &'w mut Window,
-        view: WeakView<V>,
-    ) -> Self {
+impl<'a, V: 'static> ViewContext<'a, V> {
+    pub(crate) fn new(app: &'a mut AppContext, window: &'a mut Window, view: &'a View<V>) -> Self {
         Self {
-            window_cx: WindowContext::mutable(app, window),
+            window_cx: WindowContext::new(app, window),
             view,
         }
     }
 
-    pub fn view(&self) -> WeakView<V> {
+    pub fn view(&self) -> View<V> {
         self.view.clone()
     }
 
-    pub fn model(&self) -> WeakModel<V> {
+    pub fn model(&self) -> Model<V> {
         self.view.model.clone()
     }
 
@@ -1525,40 +1578,50 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
         result
     }
 
-    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + Send + 'static)
+    pub fn on_next_frame(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static)
     where
-        V: Any + Send,
+        V: 'static,
     {
-        let view = self.view().upgrade().unwrap();
+        let view = self.view();
         self.window_cx.on_next_frame(move |cx| view.update(cx, f));
     }
 
+    /// Schedules the given function to be run at the end of the current effect cycle, allowing entities
+    /// that are currently on the stack to be returned to the app.
+    pub fn defer(&mut self, f: impl FnOnce(&mut V, &mut ViewContext<V>) + 'static) {
+        let view = self.view().downgrade();
+        self.window_cx.defer(move |cx| {
+            view.update(cx, f).ok();
+        });
+    }
+
     pub fn observe<V2, E>(
         &mut self,
         entity: &E,
-        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, '_, V>) + Send + 'static,
+        mut on_notify: impl FnMut(&mut V, E, &mut ViewContext<'_, V>) + 'static,
     ) -> Subscription
     where
         V2: 'static,
-        V: Any + Send,
+        V: 'static,
         E: Entity<V2>,
     {
-        let view = self.view();
+        let view = self.view().downgrade();
         let entity_id = entity.entity_id();
         let entity = entity.downgrade();
         let window_handle = self.window.handle;
         self.app.observers.insert(
             entity_id,
             Box::new(move |cx| {
-                cx.update_window(window_handle.id, |cx| {
-                    if let Some(handle) = E::upgrade_from(&entity) {
-                        view.update(cx, |this, cx| on_notify(this, handle, cx))
-                            .is_ok()
-                    } else {
-                        false
-                    }
-                })
-                .unwrap_or(false)
+                window_handle
+                    .update(cx, |_, cx| {
+                        if let Some(handle) = E::upgrade_from(&entity) {
+                            view.update(cx, |this, cx| on_notify(this, handle, cx))
+                                .is_ok()
+                        } else {
+                            false
+                        }
+                    })
+                    .unwrap_or(false)
             }),
         )
     }
@@ -1566,44 +1629,44 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
     pub fn subscribe<V2, E>(
         &mut self,
         entity: &E,
-        mut on_event: impl FnMut(&mut V, E, &V2::Event, &mut ViewContext<'_, '_, V>) + Send + 'static,
+        mut on_event: impl FnMut(&mut V, E, &V2::Event, &mut ViewContext<'_, V>) + 'static,
     ) -> Subscription
     where
         V2: EventEmitter,
         E: Entity<V2>,
     {
-        let view = self.view();
+        let view = self.view().downgrade();
         let entity_id = entity.entity_id();
         let handle = entity.downgrade();
         let window_handle = self.window.handle;
         self.app.event_listeners.insert(
             entity_id,
             Box::new(move |event, cx| {
-                cx.update_window(window_handle.id, |cx| {
-                    if let Some(handle) = E::upgrade_from(&handle) {
-                        let event = event.downcast_ref().expect("invalid event type");
-                        view.update(cx, |this, cx| on_event(this, handle, event, cx))
-                            .is_ok()
-                    } else {
-                        false
-                    }
-                })
-                .unwrap_or(false)
+                window_handle
+                    .update(cx, |_, cx| {
+                        if let Some(handle) = E::upgrade_from(&handle) {
+                            let event = event.downcast_ref().expect("invalid event type");
+                            view.update(cx, |this, cx| on_event(this, handle, event, cx))
+                                .is_ok()
+                        } else {
+                            false
+                        }
+                    })
+                    .unwrap_or(false)
             }),
         )
     }
 
     pub fn on_release(
         &mut self,
-        mut on_release: impl FnMut(&mut V, &mut WindowContext) + Send + 'static,
+        on_release: impl FnOnce(&mut V, &mut WindowContext) + 'static,
     ) -> Subscription {
         let window_handle = self.window.handle;
         self.app.release_listeners.insert(
             self.view.model.entity_id,
             Box::new(move |this, cx| {
                 let this = this.downcast_mut().expect("invalid entity type");
-                // todo!("are we okay with silently swallowing the error?")
-                let _ = cx.update_window(window_handle.id, |cx| on_release(this, cx));
+                let _ = window_handle.update(cx, |_, cx| on_release(this, cx));
             }),
         )
     }
@@ -1611,21 +1674,21 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
     pub fn observe_release<V2, E>(
         &mut self,
         entity: &E,
-        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, '_, V>) + Send + 'static,
+        mut on_release: impl FnMut(&mut V, &mut V2, &mut ViewContext<'_, V>) + 'static,
     ) -> Subscription
     where
-        V: Any + Send,
+        V: 'static,
         V2: 'static,
         E: Entity<V2>,
     {
-        let view = self.view();
+        let view = self.view().downgrade();
         let entity_id = entity.entity_id();
         let window_handle = self.window.handle;
         self.app.release_listeners.insert(
             entity_id,
             Box::new(move |entity, cx| {
                 let entity = entity.downcast_mut().expect("invalid entity type");
-                let _ = cx.update_window(window_handle.id, |cx| {
+                let _ = window_handle.update(cx, |_, cx| {
                     view.update(cx, |this, cx| on_release(this, entity, cx))
                 });
             }),
@@ -1641,9 +1704,9 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
 
     pub fn on_focus_changed(
         &mut self,
-        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + Send + 'static,
+        listener: impl Fn(&mut V, &FocusEvent, &mut ViewContext<V>) + 'static,
     ) {
-        let handle = self.view();
+        let handle = self.view().downgrade();
         self.window.focus_listeners.push(Box::new(move |event, cx| {
             handle
                 .update(cx, |view, cx| listener(view, event, cx))
@@ -1659,12 +1722,12 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
         let old_stack_len = self.window.key_dispatch_stack.len();
         if !self.window.freeze_key_dispatch_stack {
             for (event_type, listener) in key_listeners {
-                let handle = self.view();
+                let handle = self.view().downgrade();
                 let listener = Box::new(
                     move |event: &dyn Any,
                           context_stack: &[&DispatchContext],
                           phase: DispatchPhase,
-                          cx: &mut WindowContext<'_, '_>| {
+                          cx: &mut WindowContext<'_>| {
                         handle
                             .update(cx, |view, cx| {
                                 listener(view, event, context_stack, phase, cx)
@@ -1745,16 +1808,13 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
         R: 'static,
         Fut: Future<Output = R> + 'static,
     {
-        let view = self.view();
-        self.window_cx.spawn(move |_, cx| {
-            let result = f(view, cx);
-            async move { result.await }
-        })
+        let view = self.view().downgrade();
+        self.window_cx.spawn(move |_, cx| f(view, cx))
     }
 
     pub fn update_global<G, R>(&mut self, f: impl FnOnce(&mut G, &mut Self) -> R) -> R
     where
-        G: 'static + Send,
+        G: 'static,
     {
         let mut global = self.app.lease_global::<G>();
         let result = f(&mut global, self);
@@ -1764,17 +1824,16 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
 
     pub fn observe_global<G: 'static>(
         &mut self,
-        f: impl Fn(&mut V, &mut ViewContext<'_, '_, V>) + Send + 'static,
+        f: impl Fn(&mut V, &mut ViewContext<'_, V>) + 'static,
     ) -> Subscription {
-        let window_id = self.window.handle.id;
-        let handle = self.view();
+        let window_handle = self.window.handle;
+        let view = self.view().downgrade();
         self.global_observers.insert(
             TypeId::of::<G>(),
             Box::new(move |cx| {
-                cx.update_window(window_id, |cx| {
-                    handle.update(cx, |view, cx| f(view, cx)).is_ok()
-                })
-                .unwrap_or(false)
+                window_handle
+                    .update(cx, |_, cx| view.update(cx, |view, cx| f(view, cx)).is_ok())
+                    .unwrap_or(false)
             }),
         )
     }
@@ -1783,7 +1842,7 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
         &mut self,
         handler: impl Fn(&mut V, &Event, DispatchPhase, &mut ViewContext<V>) + 'static,
     ) {
-        let handle = self.view().upgrade().unwrap();
+        let handle = self.view();
         self.window_cx.on_mouse_event(move |event, phase, cx| {
             handle.update(cx, |view, cx| {
                 handler(view, event, phase, cx);
@@ -1792,10 +1851,10 @@ impl<'a, 'w, V: 'static> ViewContext<'a, 'w, V> {
     }
 }
 
-impl<'a, 'w, V> ViewContext<'a, 'w, V>
+impl<V> ViewContext<'_, V>
 where
     V: EventEmitter,
-    V::Event: Any + Send,
+    V::Event: 'static,
 {
     pub fn emit(&mut self, event: V::Event) {
         let emitter = self.view.model.entity_id;
@@ -1806,13 +1865,12 @@ where
     }
 }
 
-impl<'a, 'w, V> Context for ViewContext<'a, 'w, V> {
-    type ModelContext<'b, U> = ModelContext<'b, U>;
+impl<V> Context for ViewContext<'_, V> {
     type Result<U> = U;
 
     fn build_model<T: 'static>(
         &mut self,
-        build_model: impl FnOnce(&mut Self::ModelContext<'_, T>) -> T,
+        build_model: impl FnOnce(&mut ModelContext<'_, T>) -> T,
     ) -> Model<T> {
         self.window_cx.build_model(build_model)
     }
@@ -1820,18 +1878,23 @@ impl<'a, 'w, V> Context for ViewContext<'a, 'w, V> {
     fn update_model<T: 'static, R>(
         &mut self,
         model: &Model<T>,
-        update: impl FnOnce(&mut T, &mut Self::ModelContext<'_, T>) -> R,
+        update: impl FnOnce(&mut T, &mut ModelContext<'_, T>) -> R,
     ) -> R {
         self.window_cx.update_model(model, update)
     }
+
+    fn update_window<T, F>(&mut self, window: AnyWindowHandle, update: F) -> Result<T>
+    where
+        F: FnOnce(AnyView, &mut WindowContext<'_>) -> T,
+    {
+        self.window_cx.update_window(window, update)
+    }
 }
 
-impl<V: 'static> VisualContext for ViewContext<'_, '_, V> {
-    type ViewContext<'a, 'w, V2> = ViewContext<'a, 'w, V2>;
-
+impl<V: 'static> VisualContext for ViewContext<'_, V> {
     fn build_view<W: 'static>(
         &mut self,
-        build_view: impl FnOnce(&mut Self::ViewContext<'_, '_, W>) -> W,
+        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
     ) -> Self::Result<View<W>> {
         self.window_cx.build_view(build_view)
     }
@@ -1839,21 +1902,31 @@ impl<V: 'static> VisualContext for ViewContext<'_, '_, V> {
     fn update_view<V2: 'static, R>(
         &mut self,
         view: &View<V2>,
-        update: impl FnOnce(&mut V2, &mut Self::ViewContext<'_, '_, V2>) -> R,
+        update: impl FnOnce(&mut V2, &mut ViewContext<'_, V2>) -> R,
     ) -> Self::Result<R> {
         self.window_cx.update_view(view, update)
     }
+
+    fn replace_root_view<W>(
+        &mut self,
+        build_view: impl FnOnce(&mut ViewContext<'_, W>) -> W,
+    ) -> Self::Result<View<W>>
+    where
+        W: Render,
+    {
+        self.window_cx.replace_root_view(build_view)
+    }
 }
 
-impl<'a, 'w, V> std::ops::Deref for ViewContext<'a, 'w, V> {
-    type Target = WindowContext<'a, 'w>;
+impl<'a, V> std::ops::Deref for ViewContext<'a, V> {
+    type Target = WindowContext<'a>;
 
     fn deref(&self) -> &Self::Target {
         &self.window_cx
     }
 }
 
-impl<'a, 'w, V> std::ops::DerefMut for ViewContext<'a, 'w, V> {
+impl<'a, V> std::ops::DerefMut for ViewContext<'a, V> {
     fn deref_mut(&mut self) -> &mut Self::Target {
         &mut self.window_cx
     }
@@ -1868,42 +1941,74 @@ impl WindowId {
     }
 }
 
-#[derive(PartialEq, Eq)]
+#[derive(Deref, DerefMut)]
 pub struct WindowHandle<V> {
-    id: WindowId,
+    #[deref]
+    #[deref_mut]
+    pub(crate) any_handle: AnyWindowHandle,
     state_type: PhantomData<V>,
 }
 
-impl<S> Copy for WindowHandle<S> {}
-
-impl<S> Clone for WindowHandle<S> {
-    fn clone(&self) -> Self {
-        WindowHandle {
-            id: self.id,
-            state_type: PhantomData,
-        }
-    }
-}
-
-impl<S> WindowHandle<S> {
+impl<V: 'static + Render> WindowHandle<V> {
     pub fn new(id: WindowId) -> Self {
         WindowHandle {
-            id,
+            any_handle: AnyWindowHandle {
+                id,
+                state_type: TypeId::of::<V>(),
+            },
+            state_type: PhantomData,
+        }
+    }
+
+    pub fn update<C, R>(
+        self,
+        cx: &mut C,
+        update: impl FnOnce(&mut V, &mut ViewContext<'_, V>) -> R,
+    ) -> Result<R>
+    where
+        C: Context,
+    {
+        cx.update_window(self.any_handle, |root_view, cx| {
+            let view = root_view
+                .downcast::<V>()
+                .map_err(|_| anyhow!("the type of the window's root view has changed"))?;
+            Ok(cx.update_view(&view, update))
+        })?
+    }
+}
+
+impl<V> Copy for WindowHandle<V> {}
+
+impl<V> Clone for WindowHandle<V> {
+    fn clone(&self) -> Self {
+        WindowHandle {
+            any_handle: self.any_handle,
             state_type: PhantomData,
         }
     }
 }
 
-impl<S: 'static> Into<AnyWindowHandle> for WindowHandle<S> {
-    fn into(self) -> AnyWindowHandle {
-        AnyWindowHandle {
-            id: self.id,
-            state_type: TypeId::of::<S>(),
-        }
+impl<V> PartialEq for WindowHandle<V> {
+    fn eq(&self, other: &Self) -> bool {
+        self.any_handle == other.any_handle
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Eq)]
+impl<V> Eq for WindowHandle<V> {}
+
+impl<V> Hash for WindowHandle<V> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.any_handle.hash(state);
+    }
+}
+
+impl<V: 'static> Into<AnyWindowHandle> for WindowHandle<V> {
+    fn into(self) -> AnyWindowHandle {
+        self.any_handle
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, Hash)]
 pub struct AnyWindowHandle {
     pub(crate) id: WindowId,
     state_type: TypeId,
@@ -1913,6 +2018,28 @@ impl AnyWindowHandle {
     pub fn window_id(&self) -> WindowId {
         self.id
     }
+
+    pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>> {
+        if TypeId::of::<T>() == self.state_type {
+            Some(WindowHandle {
+                any_handle: *self,
+                state_type: PhantomData,
+            })
+        } else {
+            None
+        }
+    }
+
+    pub fn update<C, R>(
+        self,
+        cx: &mut C,
+        update: impl FnOnce(AnyView, &mut WindowContext<'_>) -> R,
+    ) -> Result<R>
+    where
+        C: Context,
+    {
+        cx.update_window(self, update)
+    }
 }
 
 #[cfg(any(test, feature = "test-support"))]