diff --git a/backends/imgui_impl_glfw.cpp b/backends/imgui_impl_glfw.cpp
index 10be0b304..3bafa5d1f 100644
--- a/backends/imgui_impl_glfw.cpp
+++ b/backends/imgui_impl_glfw.cpp
@@ -162,7 +162,7 @@ struct ImGui_ImplGlfw_Data
     GLFWcharfun             PrevUserCallbackChar;
     GLFWmonitorfun          PrevUserCallbackMonitor;
 #ifdef _WIN32
-    WNDPROC                 GlfwWndProc;
+    WNDPROC                 PrevWndProc;
 #endif
 
     ImGui_ImplGlfw_Data()   { memset((void*)this, 0, sizeof(*this)); }
@@ -494,48 +494,7 @@ static EM_BOOL ImGui_ImplEmscripten_WheelCallback(int, const EmscriptenWheelEven
 #endif
 
 #ifdef _WIN32
-// GLFW doesn't allow to distinguish Mouse vs TouchScreen vs Pen.
-// Add support for Win32 (based on imgui_impl_win32), because we rely on _TouchScreen info to trickle inputs differently.
-static ImGuiMouseSource GetMouseSourceFromMessageExtraInfo()
-{
-    LPARAM extra_info = ::GetMessageExtraInfo();
-    if ((extra_info & 0xFFFFFF80) == 0xFF515700)
-        return ImGuiMouseSource_Pen;
-    if ((extra_info & 0xFFFFFF80) == 0xFF515780)
-        return ImGuiMouseSource_TouchScreen;
-    return ImGuiMouseSource_Mouse;
-}
-static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
-{
-    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
-    switch (msg)
-    {
-    case WM_MOUSEMOVE: case WM_NCMOUSEMOVE:
-    case WM_LBUTTONDOWN: case WM_LBUTTONDBLCLK: case WM_LBUTTONUP:
-    case WM_RBUTTONDOWN: case WM_RBUTTONDBLCLK: case WM_RBUTTONUP:
-    case WM_MBUTTONDOWN: case WM_MBUTTONDBLCLK: case WM_MBUTTONUP:
-    case WM_XBUTTONDOWN: case WM_XBUTTONDBLCLK: case WM_XBUTTONUP:
-        ImGui::GetIO().AddMouseSourceEvent(GetMouseSourceFromMessageExtraInfo());
-        break;
-
-    // We have submitted https://github.com/glfw/glfw/pull/1568 to allow GLFW to support "transparent inputs".
-    // In the meanwhile we implement custom per-platform workarounds here (FIXME-VIEWPORT: Implement same work-around for Linux/OSX!)
-#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED
-    case WM_NCHITTEST:
-    {
-        // Let mouse pass-through the window. This will allow the backend to call io.AddMouseViewportEvent() properly (which is OPTIONAL).
-        // The ImGuiViewportFlags_NoInputs flag is set while dragging a viewport, as want to detect the window behind the one we are dragging.
-        // If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
-        // your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
-        ImGuiViewport* viewport = (ImGuiViewport*)::GetPropA(hWnd, "IMGUI_VIEWPORT");
-        if (viewport && (viewport->Flags & ImGuiViewportFlags_NoInputs))
-            return HTTRANSPARENT;
-        break;
-    }
-#endif
-    }
-    return ::CallWindowProc(bd->GlfwWndProc, hWnd, msg, wParam, lParam);
-}
+static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);
 #endif
 
 void ImGui_ImplGlfw_InstallCallbacks(GLFWwindow* window)
@@ -672,8 +631,8 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
 
     // Windows: register a WndProc hook so we can intercept some messages.
 #ifdef _WIN32
-    bd->GlfwWndProc = (WNDPROC)::GetWindowLongPtr((HWND)main_viewport->PlatformHandleRaw, GWLP_WNDPROC);
-    IM_ASSERT(bd->GlfwWndProc != nullptr);
+    bd->PrevWndProc = (WNDPROC)::GetWindowLongPtr((HWND)main_viewport->PlatformHandleRaw, GWLP_WNDPROC);
+    IM_ASSERT(bd->PrevWndProc != nullptr);
     ::SetWindowLongPtr((HWND)main_viewport->PlatformHandleRaw, GWLP_WNDPROC, (LONG_PTR)ImGui_ImplGlfw_WndProc);
 #endif
 
@@ -713,11 +672,11 @@ void ImGui_ImplGlfw_Shutdown()
     for (ImGuiMouseCursor cursor_n = 0; cursor_n < ImGuiMouseCursor_COUNT; cursor_n++)
         glfwDestroyCursor(bd->MouseCursors[cursor_n]);
 
-    // Windows: register a WndProc hook so we can intercept some messages.
+    // Windows: restore our WndProc hook
 #ifdef _WIN32
     ImGuiViewport* main_viewport = ImGui::GetMainViewport();
-    ::SetWindowLongPtr((HWND)main_viewport->PlatformHandleRaw, GWLP_WNDPROC, (LONG_PTR)bd->GlfwWndProc);
-    bd->GlfwWndProc = nullptr;
+    ::SetWindowLongPtr((HWND)main_viewport->PlatformHandleRaw, GWLP_WNDPROC, (LONG_PTR)bd->PrevWndProc);
+    bd->PrevWndProc = nullptr;
 #endif
 
     io.BackendPlatformName = nullptr;
@@ -1102,7 +1061,7 @@ static void ImGui_ImplGlfw_ShowWindow(ImGuiViewport* viewport)
 #if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED && defined(_WIN32)
     ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
     ::SetPropA(hwnd, "IMGUI_VIEWPORT", viewport);
-    IM_ASSERT(bd->GlfwWndProc == (WNDPROC)::GetWindowLongPtr(hwnd, GWLP_WNDPROC));
+    IM_ASSERT(bd->PrevWndProc == (WNDPROC)::GetWindowLongPtr(hwnd, GWLP_WNDPROC));
     ::SetWindowLongPtr(hwnd, GWLP_WNDPROC, (LONG_PTR)ImGui_ImplGlfw_WndProc);
 #endif
 
@@ -1290,6 +1249,54 @@ static void ImGui_ImplGlfw_ShutdownPlatformInterface()
 
 //-----------------------------------------------------------------------------
 
+// WndProc hook (declared here because we will need access to ImGui_ImplGlfw_ViewportData) 
+#ifdef _WIN32
+static ImGuiMouseSource GetMouseSourceFromMessageExtraInfo()
+{
+    LPARAM extra_info = ::GetMessageExtraInfo();
+    if ((extra_info & 0xFFFFFF80) == 0xFF515700)
+        return ImGuiMouseSource_Pen;
+    if ((extra_info & 0xFFFFFF80) == 0xFF515780)
+        return ImGuiMouseSource_TouchScreen;
+    return ImGuiMouseSource_Mouse;
+}
+static LRESULT CALLBACK ImGui_ImplGlfw_WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
+{
+    ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
+    switch (msg)
+    {
+        // GLFW doesn't allow to distinguish Mouse vs TouchScreen vs Pen.
+        // Add support for Win32 (based on imgui_impl_win32), because we rely on _TouchScreen info to trickle inputs differently.
+    case WM_MOUSEMOVE: case WM_NCMOUSEMOVE:
+    case WM_LBUTTONDOWN: case WM_LBUTTONDBLCLK: case WM_LBUTTONUP:
+    case WM_RBUTTONDOWN: case WM_RBUTTONDBLCLK: case WM_RBUTTONUP:
+    case WM_MBUTTONDOWN: case WM_MBUTTONDBLCLK: case WM_MBUTTONUP:
+    case WM_XBUTTONDOWN: case WM_XBUTTONDBLCLK: case WM_XBUTTONUP:
+        ImGui::GetIO().AddMouseSourceEvent(GetMouseSourceFromMessageExtraInfo());
+        break;
+
+        // We have submitted https://github.com/glfw/glfw/pull/1568 to allow GLFW to support "transparent inputs".
+        // In the meanwhile we implement custom per-platform workarounds here (FIXME-VIEWPORT: Implement same work-around for Linux/OSX!)
+#if !GLFW_HAS_MOUSE_PASSTHROUGH && GLFW_HAS_WINDOW_HOVERED
+    case WM_NCHITTEST:
+    {
+        // Let mouse pass-through the window. This will allow the backend to call io.AddMouseViewportEvent() properly (which is OPTIONAL).
+        // The ImGuiViewportFlags_NoInputs flag is set while dragging a viewport, as want to detect the window behind the one we are dragging.
+        // If you cannot easily access those viewport flags from your windowing/event code: you may manually synchronize its state e.g. in
+        // your main loop after calling UpdatePlatformWindows(). Iterate all viewports/platform windows and pass the flag to your windowing system.
+        ImGuiViewport* viewport = (ImGuiViewport*)::GetPropA(hWnd, "IMGUI_VIEWPORT");
+        if (viewport && (viewport->Flags & ImGuiViewportFlags_NoInputs))
+            return HTTRANSPARENT;
+        break;
+    }
+#endif
+    }
+    return ::CallWindowProc(bd->PrevWndProc, hWnd, msg, wParam, lParam);
+}
+#endif // #ifdef _WIN32
+
+//-----------------------------------------------------------------------------
+
 #if defined(__clang__)
 #pragma clang diagnostic pop
 #endif