15 files changed, 272 insertions, 313 deletions

diff --git a/include/cru/ui/Base.h b/include/cru/ui/Base.h
index 9e24cfa2..06dd23c2 100644
--- a/include/cru/ui/Base.h
+++ b/include/cru/ui/Base.h
@@ -35,7 +35,7 @@ namespace colors = cru::platform::colors;
 
 namespace controls {
 class Control;
-class Window;
+class ControlHost;
 }  // namespace controls
 
 //-------------------- region: basic types --------------------
diff --git a/include/cru/ui/controls/Button.h b/include/cru/ui/controls/Button.h
index e8fa50f1..64b9bba0 100644
--- a/include/cru/ui/controls/Button.h
+++ b/include/cru/ui/controls/Button.h
@@ -16,10 +16,6 @@ class CRU_UI_API Button : public SingleChildControl<render::BorderRenderObject>,
 
  public:
   Button();
-  Button(const Button& other) = delete;
-  Button(Button&& other) = delete;
-  Button& operator=(const Button& other) = delete;
-  Button& operator=(Button&& other) = delete;
   ~Button() override;
 
   std::string GetControlType() const final { return std::string(kControlType); }
diff --git a/include/cru/ui/controls/CheckBox.h b/include/cru/ui/controls/CheckBox.h
index 8a2c84a0..6f4eae2e 100644
--- a/include/cru/ui/controls/CheckBox.h
+++ b/include/cru/ui/controls/CheckBox.h
@@ -1,13 +1,13 @@
 #pragma once
 #include "../helper/ClickDetector.h"
 #include "../render/BorderRenderObject.h"
+#include "Control.h"
 #include "IBorderControl.h"
 #include "ICheckableControl.h"
 #include "IClickableControl.h"
-#include "NoChildControl.h"
 
 namespace cru::ui::controls {
-class CRU_UI_API CheckBox : public NoChildControl,
+class CRU_UI_API CheckBox : public Control,
                             public virtual IBorderControl,
                             public virtual ICheckableControl,
                             public virtual IClickableControl {
@@ -17,7 +17,9 @@ class CRU_UI_API CheckBox : public NoChildControl,
   CheckBox();
   ~CheckBox() override;
 
-  std::string GetControlType() const override { return std::string(kControlType); }
+  std::string GetControlType() const override {
+    return std::string(kControlType);
+  }
 
   render::RenderObject* GetRenderObject() const override {
     return container_render_object_.get();
diff --git a/include/cru/ui/controls/Control.h b/include/cru/ui/controls/Control.h
index 94de4cdc..9e5e86b8 100644
--- a/include/cru/ui/controls/Control.h
+++ b/include/cru/ui/controls/Control.h
@@ -24,9 +24,9 @@ namespace cru::ui::controls {
 class CRU_UI_API Control : public Object,
                            public DeleteLaterImpl,
                            public SelfResolvable<Control> {
-  friend class RootControl;
+  friend class ControlHost;
 
-  CRU_DEFINE_CLASS_LOG_TAG("Control")
+  CRU_DEFINE_CLASS_LOG_TAG("cru::ui::controls::Control")
 
  protected:
   Control();
@@ -41,24 +41,33 @@ class CRU_UI_API Control : public Object,
 
   //*************** region: tree ***************
  public:
-  Window* GetWindow();
+  ControlHost* GetControlHost();
 
-  Control* GetParent() const { return parent_; }
-  void SetParent(Control* parent);
+  Control* GetParent();
   bool HasAncestor(Control* control);
+  const std::vector<Control*>& GetChildren();
+  void RemoveChild(Control* child);
+  void RemoveAllChild();
+  void RemoveFromParent();
 
-  virtual void ForEachChild(const std::function<void(Control*)>& predicate) = 0;
-
-  /**
-   *  \remarks This method should be permissive, which means if the specified
-   * child control is not a real child of this then nothing will be done.
-   */
-  virtual void RemoveChild(Control* child) = 0;
+  template <typename F>
+  void TraverseDescendents(F&& f, bool include_this) {
+    if (include_this) {
+      f(this);
+    }
 
-  void RemoveFromParent();
+    for (auto child : GetChildren()) {
+      child->TraverseDescendents(std::forward<F>(f), true);
+    }
+  }
 
   controls::Control* HitTest(const Point& point);
 
+ protected:
+  void InsertChildAt(Control* control, Index index);
+  void RemoveChildAt(Index index);
+  void AddChild(Control* control);
+
  public:
   virtual render::RenderObject* GetRenderObject() const = 0;
 
@@ -89,7 +98,7 @@ class CRU_UI_API Control : public Object,
 
   //*************** region: mouse ***************
  public:
-  bool IsMouseOver() const { return is_mouse_over_; }
+  bool IsMouseOver();
 
   bool CaptureMouse();
 
@@ -137,12 +146,14 @@ class CRU_UI_API Control : public Object,
 
   //*************** region: tree ***************
  protected:
-  virtual void OnParentChanged(Control* old_parent, Control* new_parent) {}
+  virtual void OnParentChanged(Control* old_parent, Control* new_parent);
+  virtual void OnChildInserted(Control* control, Index index);
+  virtual void OnChildRemoved(Control* control, Index index);
 
  private:
+  ControlHost* host_ = nullptr;
   Control* parent_ = nullptr;
-
-  bool is_mouse_over_ = false;
+  std::vector<Control*> children_;
 
   std::shared_ptr<platform::gui::ICursor> cursor_ = nullptr;
 
diff --git a/include/cru/ui/controls/ControlHost.h b/include/cru/ui/controls/ControlHost.h
new file mode 100644
index 00000000..c67e8a72
--- /dev/null
+++ b/include/cru/ui/controls/ControlHost.h
@@ -0,0 +1,191 @@
+#pragma once
+#include "Control.h"
+
+#include <cru/base/Base.h>
+#include <cru/base/Event.h>
+#include <cru/base/Guard.h>
+#include <cru/base/log/Logger.h>
+#include <cru/platform/gui/UiApplication.h>
+#include <cru/platform/gui/Window.h>
+
+namespace cru::ui::controls {
+class CRU_UI_API ControlHost : public Object {
+  CRU_DEFINE_CLASS_LOG_TAG("cru::ui::controls::ControlHost")
+  friend Control;
+
+ public:
+  explicit ControlHost(Control* root_control);
+  ~ControlHost() override;
+
+  platform::gui::INativeWindow* GetNativeWindow();
+
+  void InvalidateLayout();
+  void InvalidatePaint();
+
+  void Repaint();
+  void Relayout();
+  void RelayoutWithSize(const Size& available_size = Size::Infinite(),
+                        bool set_window_size_to_fit_content = false);
+
+  // If true, preferred size of root render object is set to window size when
+  // measure. Default is true.
+  bool IsLayoutPreferToFillWindow() const;
+  void SetLayoutPreferToFillWindow(bool value);
+
+  // Get current control that mouse hovers on. This ignores the mouse-capture
+  // control. Even when mouse is captured by another control, this function
+  // return the control under cursor. You can use `GetMouseCaptureControl` to
+  // get more info.
+  Control* GetMouseHoverControl() const { return mouse_hover_control_; }
+
+  Control* GetFocusControl();
+  void SetFocusControl(Control* control);
+
+  Control* GetMouseCaptureControl();
+  bool SetMouseCaptureControl(Control* control);
+
+  std::shared_ptr<platform::gui::ICursor> GetOverrideCursor();
+  void SetOverrideCursor(std::shared_ptr<platform::gui::ICursor> cursor);
+
+  bool IsInEventHandling();
+
+  CRU_DEFINE_EVENT(AfterLayout, std::nullptr_t)
+
+ private:
+  std::unique_ptr<platform::gui::INativeWindow> CreateNativeWindow();
+
+  void OnNativeDestroy(platform::gui::INativeWindow* window, std::nullptr_t);
+  void OnNativePaint(platform::gui::INativeWindow* window, std::nullptr_t);
+  void OnNativeResize(platform::gui::INativeWindow* window, const Size& size);
+  void OnNativeFocus(platform::gui::INativeWindow* window,
+                     cru::platform::gui::FocusChangeType focus);
+  void OnNativeMouseEnterLeave(platform::gui::INativeWindow* window,
+                               cru::platform::gui::MouseEnterLeaveType enter);
+  void OnNativeMouseMove(platform::gui::INativeWindow* window,
+                         const Point& point);
+  void OnNativeMouseDown(platform::gui::INativeWindow* window,
+                         const platform::gui::NativeMouseButtonEventArgs& args);
+  void OnNativeMouseUp(platform::gui::INativeWindow* window,
+                       const platform::gui::NativeMouseButtonEventArgs& args);
+  void OnNativeMouseWheel(platform::gui::INativeWindow* window,
+                          const platform::gui::NativeMouseWheelEventArgs& args);
+  void OnNativeKeyDown(platform::gui::INativeWindow* window,
+                       const platform::gui::NativeKeyEventArgs& args);
+  void OnNativeKeyUp(platform::gui::INativeWindow* window,
+                     const platform::gui::NativeKeyEventArgs& args);
+
+  void DispatchFocusControlChangeEvent(Control* old_control,
+                                       Control* new_control, bool is_window);
+  void DispatchMouseHoverControlChangeEvent(Control* old_control,
+                                            Control* new_control,
+                                            const Point& point, bool no_leave,
+                                            bool no_enter);
+
+  template <typename EventArgs, typename... Args>
+  void DispatchEvent(Control* const original_sender,
+                     events::RoutedEvent<EventArgs>* (Control::*event_ptr)(),
+                     Control* const last_receiver, Args&&... args) {
+    constexpr auto kLogTag = "cru::ui::controls::DispatchEvent";
+
+    event_handling_count_++;
+    Guard event_handling_count_guard([this] { event_handling_count_--; });
+
+    if (original_sender == nullptr || original_sender == last_receiver) return;
+
+    std::string log = "Begin dispatching routed event " +
+                      (original_sender->*event_ptr)()->GetName() +
+                      ":\n\tTunnel:";
+
+    Guard logging_guard([&] {
+      log += "\nEnd dispatching routed event " +
+             (original_sender->*event_ptr)()->GetName() + ".";
+      CRU_LOG_TAG_DEBUG("{}", log);
+    });
+
+    std::vector<ObjectResolver<Control>> receive_list;
+
+    auto parent = original_sender;
+    while (parent != last_receiver) {
+      receive_list.push_back(parent->CreateResolver());
+      parent = parent->GetParent();
+    }
+
+    auto handled = false;
+
+    // tunnel
+    for (auto i = receive_list.crbegin(); i != receive_list.crend(); ++i) {
+      auto control = i->Resolve();
+      log += " ";
+      if (!control) {
+        log += "(deleted)";
+        continue;
+      }
+      log += control->GetDebugId();
+      EventArgs event_args(control, original_sender,
+                           std::forward<Args>(args)...);
+      (control->*event_ptr)()->tunnel_.Raise(event_args);
+      if (event_args.IsHandled()) {
+        log += " marked as handled.";
+        handled = true;
+        break;
+      }
+    }
+
+    // bubble
+    if (!handled) {
+      log += "\n\tBubble:";
+      for (auto resolver : receive_list) {
+        auto control = resolver.Resolve();
+        log += " ";
+        if (!control) {
+          log += "(deleted)";
+          continue;
+        }
+        log += control->GetDebugId();
+        EventArgs event_args(control, original_sender,
+                             std::forward<Args>(args)...);
+        (control->*event_ptr)()->bubble_.Raise(event_args);
+        if (event_args.IsHandled()) {
+          log += " marked as handled.";
+          break;
+        }
+      }
+    }
+
+    log += "\n\tDirect:";
+    // direct
+    for (auto resolver : receive_list) {
+      auto control = resolver.Resolve();
+      log += " ";
+      if (!control) {
+        log += "(deleted)";
+        continue;
+      }
+      log += control->GetDebugId();
+      EventArgs event_args(control, original_sender,
+                           std::forward<Args>(args)...);
+      (control->*event_ptr)()->direct_.Raise(event_args);
+    }
+  }
+
+  void UpdateCursor();
+  void NotifyControlParentChange(Control* control, Control* old_parent, Control* new_parent);
+
+ private:
+  int event_handling_count_;
+
+  Control* root_control_;
+  std::unique_ptr<platform::gui::INativeWindow> native_window_;
+
+  Control* focus_control_;
+  Control* mouse_hover_control_;
+  Control* mouse_captured_control_;
+
+  std::shared_ptr<platform::gui::ICursor> override_cursor_;
+
+  bool layout_prefer_to_fill_window_;
+
+  platform::gui::TimerAutoCanceler repaint_schedule_canceler_;
+  platform::gui::TimerAutoCanceler relayout_schedule_canceler_;
+};
+}  // namespace cru::ui::controls
diff --git a/include/cru/ui/controls/IconButton.h b/include/cru/ui/controls/IconButton.h
index e52d2a26..0bbda327 100644
--- a/include/cru/ui/controls/IconButton.h
+++ b/include/cru/ui/controls/IconButton.h
@@ -1,18 +1,17 @@
 #pragma once
-#include <memory>
-#include "NoChildControl.h"
-
 #include "../helper/ClickDetector.h"
 #include "../render/BorderRenderObject.h"
 #include "../render/GeometryRenderObject.h"
+#include "Control.h"
 #include "IBorderControl.h"
 #include "IClickableControl.h"
 #include "IContentBrushControl.h"
-#include "cru/base/Event.h"
-#include "cru/platform/graphics/Brush.h"
+
+#include <cru/base/Event.h>
+#include <cru/platform/graphics/Brush.h>
 
 namespace cru::ui::controls {
-class CRU_UI_API IconButton : public NoChildControl,
+class CRU_UI_API IconButton : public Control,
                               public virtual IClickableControl,
                               public virtual IBorderControl,
                               public virtual IContentBrushControl {
diff --git a/include/cru/ui/controls/LayoutControl.h b/include/cru/ui/controls/LayoutControl.h
index 54407a3f..fad86530 100644
--- a/include/cru/ui/controls/LayoutControl.h
+++ b/include/cru/ui/controls/LayoutControl.h
@@ -10,17 +10,14 @@ class LayoutControl : public Control {
   }
 
  public:
-  LayoutControl(const LayoutControl& other) = delete;
-  LayoutControl(LayoutControl&& other) = delete;
-  LayoutControl& operator=(const LayoutControl& other) = delete;
-  LayoutControl& operator=(LayoutControl&& other) = delete;
-  ~LayoutControl() override { ClearChildren(); }
+  using Control::AddChild;
+  using Control::InsertChildAt;
+  using Control::RemoveChildAt;
 
- public:
-  const std::vector<Control*>& GetChildren() const { return children_; }
   Index GetChildCount() const { return children_.size(); }
-  Control* GetChild(Index index) const { return children_[index]; }
-  Index IndexOf(Control* control) const {
+  Control* GetChildAt(Index index) const { return children_[index]; }
+
+  Index IndexOfChild(Control* control) const {
     auto it = std::find(children_.begin(), children_.end(), control);
     if (it == children_.end()) {
       return -1;
@@ -28,19 +25,6 @@ class LayoutControl : public Control {
     return it - children_.begin();
   }
 
-  void ForEachChild(const std::function<void(Control*)>& callback) override {
-    for (auto child : children_) {
-      callback(child);
-    }
-  }
-
-  void RemoveChild(Control* child) override {
-    auto index = IndexOf(child);
-    if (index != -1) {
-      RemoveChildAt(index);
-    }
-  }
-
   render::RenderObject* GetRenderObject() const override {
     return container_render_object_.get();
   }
@@ -49,36 +33,6 @@ class LayoutControl : public Control {
     return container_render_object_.get();
   }
 
-  void AddChildAt(Control* child, Index position) {
-    Expects(child);
-    Expects(child->GetParent() == nullptr);
-    if (position < 0) position = 0;
-    if (position > children_.size()) position = children_.size();
-    children_.insert(children_.begin() + position, child);
-    child->SetParent(this);
-
-    assert(child->GetRenderObject());
-    container_render_object_->AddChild(child->GetRenderObject(), position);
-  }
-
-  void AddChild(Control* child) { AddChildAt(child, GetChildCount()); }
-
-  void RemoveChildAt(Index position) {
-    if (position < 0 || position >= children_.size()) return;
-    auto child = children_[position];
-    children_.erase(children_.begin() + position);
-    container_render_object_->RemoveChild(position);
-    child->SetParent(nullptr);
-  }
-
-  void ClearChildren() {
-    container_render_object_->ClearChildren();
-    for (auto child : children_) {
-      child->SetParent(nullptr);
-    }
-    children_.clear();
-  }
-
   const typename TRenderObject::ChildLayoutData& GetChildLayoutData(
       Index position) {
     return container_render_object_->GetChildLayoutDataAt(position);
@@ -89,6 +43,15 @@ class LayoutControl : public Control {
     container_render_object_->SetChildLayoutDataAt(position, data);
   }
 
+ protected:
+  void OnChildInserted(Control* control, Index index) override {
+    container_render_object_->AddChild(control->GetRenderObject(), index);
+  }
+
+  void OnChildRemoved([[maybe_unused]] Control* control, Index index) override {
+    container_render_object_->RemoveChild(index);
+  }
+
  private:
   std::unique_ptr<TRenderObject> container_render_object_;
 
diff --git a/include/cru/ui/controls/NoChildControl.h b/include/cru/ui/controls/NoChildControl.h
deleted file mode 100644
index f22fd85e..00000000
--- a/include/cru/ui/controls/NoChildControl.h
+++ /dev/null
@@ -1,21 +0,0 @@
-#pragma once
-#include "Control.h"
-
-namespace cru::ui::controls {
-class CRU_UI_API NoChildControl : public Control {
- protected:
-  NoChildControl() = default;
-
- public:
-  NoChildControl(const NoChildControl& other) = delete;
-  NoChildControl(NoChildControl&& other) = delete;
-  NoChildControl& operator=(const NoChildControl& other) = delete;
-  NoChildControl& operator=(NoChildControl&& other) = delete;
-  ~NoChildControl() override = default;
-
- public:
-  void ForEachChild(const std::function<void(Control*)>& callback) override;
-
-  void RemoveChild(Control* child) override;
-};
-}  // namespace cru::ui::controls
diff --git a/include/cru/ui/controls/SingleChildControl.h b/include/cru/ui/controls/SingleChildControl.h
index b2e58c5f..f748a38d 100644
--- a/include/cru/ui/controls/SingleChildControl.h
+++ b/include/cru/ui/controls/SingleChildControl.h
@@ -10,25 +10,17 @@ class SingleChildControl : public Control {
   }
 
  public:
-  CRU_DELETE_COPY(SingleChildControl)
-  CRU_DELETE_MOVE(SingleChildControl)
-
-  ~SingleChildControl() override { SetChild(nullptr); }
+  Control* GetChild() {
+    return GetChildren().empty() ? nullptr : GetChildren().front();
+  }
 
-  Control* GetChild() const { return child_; }
   void SetChild(Control* child) {
-    if (child == child_) return;
-
-    assert(child == nullptr || child->GetParent() == nullptr);
-
-    if (child_) {
-      child_->SetParent(nullptr);
+    if (GetChild() == child) return;
+    if (!GetChildren().empty()) {
+      RemoveChildAt(0);
     }
-
-    child_ = child;
-
     if (child) {
-      child->SetParent(this);
+      InsertChildAt(child, 0);
     }
 
     container_render_object_->SetChild(
@@ -43,20 +35,7 @@ class SingleChildControl : public Control {
     return container_render_object_.get();
   }
 
-  void ForEachChild(const std::function<void(Control*)>& predicate) override {
-    if (child_) {
-      predicate(child_);
-    }
-  }
-
-  void RemoveChild(Control* child) override {
-    if (child_ == child) {
-      SetChild(nullptr);
-    }
-  }
-
  private:
-  Control* child_ = nullptr;
   std::unique_ptr<TRenderObject> container_render_object_;
 };
 }  // namespace cru::ui::controls
diff --git a/include/cru/ui/controls/TextBlock.h b/include/cru/ui/controls/TextBlock.h
index a3b6407f..af9865c4 100644
--- a/include/cru/ui/controls/TextBlock.h
+++ b/include/cru/ui/controls/TextBlock.h
@@ -1,15 +1,15 @@
 #pragma once
-#include "NoChildControl.h"
-
+#include "Control.h"
 #include "../render/TextRenderObject.h"
 #include "IContentBrushControl.h"
 #include "IFontControl.h"
 #include "TextHostControlService.h"
-#include "cru/platform/graphics/Brush.h"
-#include "cru/platform/graphics/Font.h"
+
+#include <cru/platform/graphics/Brush.h>
+#include <cru/platform/graphics/Font.h>
 
 namespace cru::ui::controls {
-class CRU_UI_API TextBlock : public NoChildControl,
+class CRU_UI_API TextBlock : public Control,
                              public virtual ITextHostControl,
                              public virtual IFontControl,
                              public virtual IContentBrushControl {
diff --git a/include/cru/ui/controls/TextBox.h b/include/cru/ui/controls/TextBox.h
index adb9895e..4c6ef384 100644
--- a/include/cru/ui/controls/TextBox.h
+++ b/include/cru/ui/controls/TextBox.h
@@ -1,18 +1,18 @@
 #pragma once
-#include "NoChildControl.h"
-
 #include "../render/BorderRenderObject.h"
 #include "../render/TextRenderObject.h"
+#include "Control.h"
 #include "IBorderControl.h"
 #include "IContentBrushControl.h"
 #include "IFontControl.h"
 #include "TextHostControlService.h"
-#include "cru/platform/graphics/Brush.h"
+
+#include <cru/platform/graphics/Brush.h>
 
 #include <memory>
 
 namespace cru::ui::controls {
-class CRU_UI_API TextBox : public NoChildControl,
+class CRU_UI_API TextBox : public Control,
                            public virtual IBorderControl,
                            public virtual ITextHostControl,
                            public virtual IContentBrushControl,
diff --git a/include/cru/ui/controls/TreeView.h b/include/cru/ui/controls/TreeView.h
index f4938259..62b1c69b 100644
--- a/include/cru/ui/controls/TreeView.h
+++ b/include/cru/ui/controls/TreeView.h
@@ -48,6 +48,11 @@ class CRU_UI_API TreeViewItem : public Object {
 };
 
 class CRU_UI_API TreeView : public Control {
+  friend TreeViewItem;
+
+ private:
+  using Control::AddChild;
+
  public:
   constexpr static std::string_view kControlType = "TreeView";
 
@@ -61,11 +66,11 @@ class CRU_UI_API TreeView : public Control {
   }
   render::TreeRenderObject* GetRenderObject() { return &render_object_; }
 
-  void ForEachChild(const std::function<void(Control*)>& predicate) override;
-  void RemoveChild(Control* control) override;
-
   TreeViewItem* GetRootItem() { return &root_item_; }
 
+ protected:
+  void OnChildRemoved(Control* control, Index index) override;
+
  private:
   render::TreeRenderObject render_object_;
   TreeViewItem root_item_;
diff --git a/include/cru/ui/controls/Window.h b/include/cru/ui/controls/Window.h
index 88320219..a2ae01f9 100644
--- a/include/cru/ui/controls/Window.h
+++ b/include/cru/ui/controls/Window.h
@@ -19,7 +19,6 @@ class CRU_UI_API Window
   static constexpr std::string_view kControlType = "Window";
 
   Window();
-  ~Window() override;
 
   static Window* CreatePopup();
 
@@ -29,175 +28,10 @@ class CRU_UI_API Window
 
   platform::gui::INativeWindow* GetNativeWindow();
 
-  void InvalidateLayout();
-  void InvalidatePaint();
-
-  void Repaint();
-  void Relayout();
-  void RelayoutWithSize(const Size& available_size = Size::Infinite(),
-                        bool set_window_size_to_fit_content = false);
-
   void SetGainFocusOnCreateAndDestroyWhenLoseFocus(bool value);
 
-  // If true, preferred size of root render object is set to window size when
-  // measure. Default is true.
-  bool IsLayoutPreferToFillWindow() const;
-  void SetLayoutPreferToFillWindow(bool value);
-
-  // Get current control that mouse hovers on. This ignores the mouse-capture
-  // control. Even when mouse is captured by another control, this function
-  // return the control under cursor. You can use `GetMouseCaptureControl` to
-  // get more info.
-  Control* GetMouseHoverControl() const { return mouse_hover_control_; }
-
-  Control* GetFocusControl();
-  void SetFocusControl(Control* control);
-
-  Control* GetMouseCaptureControl();
-  bool SetMouseCaptureControl(Control* control);
-
-  std::shared_ptr<platform::gui::ICursor> GetOverrideCursor();
-  void SetOverrideCursor(std::shared_ptr<platform::gui::ICursor> cursor);
-
-  bool IsInEventHandling();
-
-  CRU_DEFINE_EVENT(AfterLayout, std::nullptr_t)
-
- private:
-  std::unique_ptr<platform::gui::INativeWindow> CreateNativeWindow();
-
-  void OnNativeDestroy(platform::gui::INativeWindow* window, std::nullptr_t);
-  void OnNativePaint(platform::gui::INativeWindow* window, std::nullptr_t);
-  void OnNativeResize(platform::gui::INativeWindow* window, const Size& size);
-  void OnNativeFocus(platform::gui::INativeWindow* window,
-                     cru::platform::gui::FocusChangeType focus);
-  void OnNativeMouseEnterLeave(platform::gui::INativeWindow* window,
-                               cru::platform::gui::MouseEnterLeaveType enter);
-  void OnNativeMouseMove(platform::gui::INativeWindow* window,
-                         const Point& point);
-  void OnNativeMouseDown(platform::gui::INativeWindow* window,
-                         const platform::gui::NativeMouseButtonEventArgs& args);
-  void OnNativeMouseUp(platform::gui::INativeWindow* window,
-                       const platform::gui::NativeMouseButtonEventArgs& args);
-  void OnNativeMouseWheel(platform::gui::INativeWindow* window,
-                          const platform::gui::NativeMouseWheelEventArgs& args);
-  void OnNativeKeyDown(platform::gui::INativeWindow* window,
-                       const platform::gui::NativeKeyEventArgs& args);
-  void OnNativeKeyUp(platform::gui::INativeWindow* window,
-                     const platform::gui::NativeKeyEventArgs& args);
-
-  void DispatchFocusControlChangeEvent(Control* old_control,
-                                       Control* new_control, bool is_window);
-  void DispatchMouseHoverControlChangeEvent(Control* old_control,
-                                            Control* new_control,
-                                            const Point& point, bool no_leave,
-                                            bool no_enter);
-
-  template <typename EventArgs, typename... Args>
-  void DispatchEvent(Control* const original_sender,
-                     events::RoutedEvent<EventArgs>* (Control::*event_ptr)(),
-                     Control* const last_receiver, Args&&... args) {
-    constexpr auto kLogTag = "cru::ui::controls::DispatchEvent";
-
-    event_handling_count_++;
-    Guard event_handling_count_guard([this] { event_handling_count_--; });
-
-    if (original_sender == nullptr || original_sender == last_receiver) return;
-
-    std::string log = "Begin dispatching routed event " +
-                      (original_sender->*event_ptr)()->GetName() +
-                      ":\n\tTunnel:";
-
-    Guard logging_guard([&] {
-      log += "\nEnd dispatching routed event " +
-             (original_sender->*event_ptr)()->GetName() + ".";
-      CRU_LOG_TAG_DEBUG("{}", log);
-    });
-
-    std::vector<ObjectResolver<Control>> receive_list;
-
-    auto parent = original_sender;
-    while (parent != last_receiver) {
-      receive_list.push_back(parent->CreateResolver());
-      parent = parent->GetParent();
-    }
-
-    auto handled = false;
-
-    // tunnel
-    for (auto i = receive_list.crbegin(); i != receive_list.crend(); ++i) {
-      auto control = i->Resolve();
-      log += " ";
-      if (!control) {
-        log += "(deleted)";
-        continue;
-      }
-      log += control->GetDebugId();
-      EventArgs event_args(control, original_sender,
-                           std::forward<Args>(args)...);
-      (control->*event_ptr)()->tunnel_.Raise(event_args);
-      if (event_args.IsHandled()) {
-        log += " marked as handled.";
-        handled = true;
-        break;
-      }
-    }
-
-    // bubble
-    if (!handled) {
-      log += "\n\tBubble:";
-      for (auto resolver : receive_list) {
-        auto control = resolver.Resolve();
-        log += " ";
-        if (!control) {
-          log += "(deleted)";
-          continue;
-        }
-        log += control->GetDebugId();
-        EventArgs event_args(control, original_sender,
-                             std::forward<Args>(args)...);
-        (control->*event_ptr)()->bubble_.Raise(event_args);
-        if (event_args.IsHandled()) {
-          log += " marked as handled.";
-          break;
-        }
-      }
-    }
-
-    log += "\n\tDirect:";
-    // direct
-    for (auto resolver : receive_list) {
-      auto control = resolver.Resolve();
-      log += " ";
-      if (!control) {
-        log += "(deleted)";
-        continue;
-      }
-      log += control->GetDebugId();
-      EventArgs event_args(control, original_sender,
-                           std::forward<Args>(args)...);
-      (control->*event_ptr)()->direct_.Raise(event_args);
-    }
-  }
-
-  void UpdateCursor();
-  void NotifyControlDestroyed(Control* control);
-
  private:
-  int event_handling_count_;
-
-  std::unique_ptr<platform::gui::INativeWindow> native_window_;
-
-  Control* focus_control_;
-  Control* mouse_hover_control_;
-  Control* mouse_captured_control_;
-
-  std::shared_ptr<platform::gui::ICursor> override_cursor_;
-
-  bool layout_prefer_to_fill_window_;
-
-  platform::gui::TimerAutoCanceler repaint_schedule_canceler_;
-  platform::gui::TimerAutoCanceler relayout_schedule_canceler_;
+  std::shared_ptr<ControlHost> control_host_;
 
   Control* attached_control_;
 
diff --git a/include/cru/ui/events/RoutedEvent.h b/include/cru/ui/events/RoutedEvent.h
index 58e50d63..b14b6e42 100644
--- a/include/cru/ui/events/RoutedEvent.h
+++ b/include/cru/ui/events/RoutedEvent.h
@@ -8,7 +8,7 @@ namespace cru::ui::events {
 // EventArgs must be reference because the IsHandled property must be settable.
 template <typename TEventArgs>
 class CRU_UI_API RoutedEvent {
-  friend controls::Window;
+  friend controls::ControlHost;
 
  public:
   static_assert(std::is_base_of_v<UiEventArgs, TEventArgs>,
diff --git a/include/cru/ui/render/RenderObject.h b/include/cru/ui/render/RenderObject.h
index c299ea24..4c19ad3e 100644
--- a/include/cru/ui/render/RenderObject.h
+++ b/include/cru/ui/render/RenderObject.h
@@ -137,7 +137,7 @@ class CRU_UI_API RenderObject : public Object {
   virtual RenderObject* HitTest(const Point& point) = 0;
 
  public:
-  controls::Window* GetWindow();
+  controls::ControlHost* GetControlHost();
   void InvalidateLayout();
   void InvalidatePaint();