2 files changed, 16 insertions, 13 deletions
diff --git a/include/cru/platform/native/ui_application.hpp b/include/cru/platform/native/ui_application.hpp
index b69b1f52..edbcc578 100644
--- a/include/cru/platform/native/ui_application.hpp
+++ b/include/cru/platform/native/ui_application.hpp
@@ -3,6 +3,7 @@
 
 #include <chrono>
 #include <functional>
+#include <memory>
 #include <vector>
 
 namespace cru::platform::graph {
@@ -11,6 +12,7 @@ struct IGraphFactory;
 
 namespace cru::platform::native {
 struct INativeWindow;
+struct INativeWindowResolver;
 struct ICursorManager;
 
 // The entry point of a ui application.
@@ -39,7 +41,8 @@ struct IUiApplication : public virtual INativeResource {
   virtual void CancelTimer(unsigned long id) = 0;
 
   virtual std::vector<INativeWindow*> GetAllWindow() = 0;
-  virtual INativeWindow* CreateWindow(INativeWindow* parent) = 0;
+  virtual std::shared_ptr<INativeWindowResolver> CreateWindow(
+      INativeWindow* parent) = 0;
 
   virtual cru::platform::graph::IGraphFactory* GetGraphFactory() = 0;
 
diff --git a/include/cru/platform/native/window.hpp b/include/cru/platform/native/window.hpp
index bfaf170b..84193a13 100644
--- a/include/cru/platform/native/window.hpp
+++ b/include/cru/platform/native/window.hpp
@@ -12,22 +12,17 @@ struct IPainter;
 }
 
 namespace cru::platform::native {
+struct INativeWindowResolver;
+
 // Represents a native window, which exposes some low-level events and
 // operations.
 //
-// Although you can always retain an instance of this class, the real window
-// associated with it might be have already been destroyed by explicitly calling
-// Close or closed by the user, which leads to an invalid instance. You can
-// check the validity by IsValid. When you call perform native operations on the
-// invalid instance, there is no effect.
+// Usually you save an INativeWindowResolver after creating a window. Because
+// window may be destroyed when user do certain actions like click the close
+// button. Then the INativeWindow instance is destroyed and
+// INativeWindowResolver::Resolve return nullptr to indicate the fact.
 struct INativeWindow : virtual INativeResource {
-  // Return if the window is still valid, that is, hasn't been closed or
-  // destroyed.
-  virtual bool IsValid() = 0;
-
-  // Set if the instance is deleted automatically when the window is destroyed
-  // by other ways. Default is true.
-  virtual void SetDeleteThisOnDestroy(bool value) = 0;
+  virtual std::shared_ptr<INativeWindowResolver> GetResolver() = 0;
 
   virtual void Close() = 0;
 
@@ -71,4 +66,9 @@ struct INativeWindow : virtual INativeResource {
   virtual IEvent<int>* KeyDownEvent() = 0;
   virtual IEvent<int>* KeyUpEvent() = 0;
 };
+
+// See INativeWindow for more info.
+struct INativeWindowResolver : virtual INativeResource {
+  virtual INativeWindow* Resolve() = 0;
+};
 }  // namespace cru::platform::native