Win32: Fixup

src/win32_platform.h

@@ -273,6 +273,7 @@ typedef struct _GLFWwindowWin32
     // Whether to enable framebuffer transparency on DWM
     GLFWbool            transparent;
     GLFWbool            external;
+    LONG_PTR            externalWindowProc;
 
     // The last received cursor position, regardless of source
     int                 lastCursorPosX, lastCursorPosY;

src/win32_window.c

@@ -1261,10 +1261,19 @@ void _glfwPlatformDestroyWindow(_GLFWwindow* window)
     if (_glfw.win32.disabledCursorWindow == window)
         _glfw.win32.disabledCursorWindow = NULL;
 
-    if (window->win32.handle && !window->win32.external)
+    if (window->win32.handle)
     {
         RemovePropW(window->win32.handle, L"GLFW");
-        DestroyWindow(window->win32.handle);
+
+        if (window->win32.external)
+        {
+            SetWindowLongPtrW(window->win32.handle,
+                              GWLP_WNDPROC,
+                              window->win32.externalWindowProc);
+        }
+        else
+            DestroyWindow(window->win32.handle);
+
         window->win32.handle = NULL;
     }
 
@@ -2039,10 +2048,12 @@ GLFWAPI GLFWwindow* glfwAttachWin32Window(HWND handle, GLFWwindow* share)
     window->numer       = GLFW_DONT_CARE;
     window->denom       = GLFW_DONT_CARE;
 
-    window->win32.handle   = handle;
-    window->win32.external = GLFW_TRUE;
-
+    window->win32.handle = handle;
     SetPropW(window->win32.handle, L"GLFW", window);
+
+    window->win32.external = GLFW_TRUE;
+    window->win32.externalWindowProc =
+        GetWindowLongPtrW(window->win32.handle, GWLP_WNDPROC);
     SetWindowLongPtrW(window->win32.handle, GWLP_WNDPROC, (LONG_PTR) windowProc);
 
     {

tests/native.c

@@ -38,11 +38,6 @@ static void error_callback(int error, const char* description)
     fprintf(stderr, "Error: %s\n", description);
 }
 
-static void framebuffer_size_callback(GLFWwindow* window, int width, int height)
-{
-    glViewport(0, 0, width, height);
-}
-
 static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
 {
     // This will only be used until glfwAttachWin32Window
@@ -100,8 +95,6 @@ int main(void)
     gladLoadGLLoader((GLADloadproc) glfwGetProcAddress);
     glfwSwapInterval(1);
 
-    glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
-
     while (!glfwWindowShouldClose(window))
     {
         glClear(GL_COLOR_BUFFER_BIT);