IO: added ImGuiPlatformIO::ClearPlatformHandlers(), ClearRendererHandlers(). Backends: call those on Shutdown(). (#8945, #2769)

# Conflicts:
#	backends/imgui_impl_dx10.cpp
#	backends/imgui_impl_dx11.cpp
#	backends/imgui_impl_dx12.cpp
#	backends/imgui_impl_dx9.cpp
#	backends/imgui_impl_glfw.cpp
#	backends/imgui_impl_metal.mm
#	backends/imgui_impl_opengl2.cpp
#	backends/imgui_impl_opengl3.cpp
#	backends/imgui_impl_osx.mm
#	backends/imgui_impl_sdl2.cpp
#	backends/imgui_impl_sdl3.cpp
#	backends/imgui_impl_sdlgpu3.cpp
#	backends/imgui_impl_vulkan.cpp
#	backends/imgui_impl_win32.cpp
#	docs/CHANGELOG.txt
#	imgui.h

backends/imgui_impl_allegro5.cpp

@@ -22,6 +22,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2025-09-18: Call platform_io.ClearRendererHandlers() and platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-08-12: Inputs: fixed missing support for ImGuiKey_PrintScreen under Windows, as raw Allegro 5 does not receive it.
 //  2025-08-12: Added ImGui_ImplAllegro5_SetDisplay() function to change current ALLEGRO_DISPLAY, as Allegro applications often need to do that.
 //  2025-07-07: Fixed texture update broken on some platforms where ALLEGRO_LOCK_WRITEONLY needed all texels to be rewritten.
@@ -500,6 +501,7 @@ void ImGui_ImplAllegro5_Shutdown()
     ImGui_ImplAllegro5_Data* bd = ImGui_ImplAllegro5_GetBackendData();
     IM_ASSERT(bd != nullptr && "No platform backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplAllegro5_InvalidateDeviceObjects();
     if (bd->VertexDecl)
@@ -510,6 +512,8 @@ void ImGui_ImplAllegro5_Shutdown()
     io.BackendPlatformName = io.BackendRendererName = nullptr;
     io.BackendPlatformUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_RendererHasTextures);
+    platform_io.ClearRendererHandlers();
+    platform_io.ClearPlatformHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_dx10.cpp

@@ -18,6 +18,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: DirectX10: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas.
 //  2025-05-07: DirectX10: Honor draw_data->FramebufferScale to allow for custom backends and experiment using it (consistently with other renderer backends, even though in normal condition it is not set under Windows).
 //  2025-01-06: DirectX10: Expose selected render state in ImGui_ImplDX10_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
@@ -639,14 +640,17 @@ void ImGui_ImplDX10_Shutdown()
     ImGui_ImplDX10_Data* bd = ImGui_ImplDX10_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplDX10_ShutdownMultiViewportSupport();
     ImGui_ImplDX10_InvalidateDeviceObjects();
     if (bd->pFactory) { bd->pFactory->Release(); }
     if (bd->pd3dDevice) { bd->pd3dDevice->Release(); }
+
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_dx11.cpp

@@ -19,6 +19,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: DirectX11: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas.
 //  2025-05-07: DirectX11: Honor draw_data->FramebufferScale to allow for custom backends and experiment using it (consistently with other renderer backends, even though in normal condition it is not set under Windows).
 //  2025-02-24: [Docking] Added undocumented ImGui_ImplDX11_SetSwapChainDescs() to configure swap chain creation for secondary viewports.
@@ -660,15 +661,18 @@ void ImGui_ImplDX11_Shutdown()
     ImGui_ImplDX11_Data* bd = ImGui_ImplDX11_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplDX11_ShutdownMultiViewportSupport();
     ImGui_ImplDX11_InvalidateDeviceObjects();
     if (bd->pFactory)             { bd->pFactory->Release(); }
     if (bd->pd3dDevice)           { bd->pd3dDevice->Release(); }
     if (bd->pd3dDeviceContext)    { bd->pd3dDeviceContext->Release(); }
+
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_dx12.cpp

@@ -23,6 +23,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-19: Fixed build on MinGW. (#8702, #4594)
 //  2025-06-11: DirectX12: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas.
 //  2025-05-07: DirectX12: Honor draw_data->FramebufferScale to allow for custom backends and experiment using it (consistently with other renderer backends, even though in normal condition it is not set under Windows).
@@ -983,6 +984,7 @@ void ImGui_ImplDX12_Shutdown()
     ImGui_ImplDX12_Data* bd = ImGui_ImplDX12_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     // Manually delete main viewport render resources in-case we haven't initialized for viewports
     ImGuiViewport* main_viewport = ImGui::GetMainViewport();
@@ -1002,6 +1004,7 @@ void ImGui_ImplDX12_Shutdown()
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_dx9.cpp

@@ -19,6 +19,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: DirectX9: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas.
 //  2024-10-07: DirectX9: Changed default texture sampler to Clamp instead of Repeat/Wrap.
 //  2024-02-12: DirectX9: Using RGBA format when supported by the driver to avoid CPU side conversion. (#6575)
@@ -367,13 +368,16 @@ void ImGui_ImplDX9_Shutdown()
     ImGui_ImplDX9_Data* bd = ImGui_ImplDX9_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplDX9_ShutdownMultiViewportSupport();
     ImGui_ImplDX9_InvalidateDeviceObjects();
     if (bd->pd3dDevice) { bd->pd3dDevice->Release(); }
+
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_glfw.cpp

@@ -32,6 +32,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-09-15: Content Scales are always reported as 1.0 on Wayland. FramebufferScale are always reported as 1.0 on X11. (#8920, #8921)
 //  2025-09-10: [Docking] Improve multi-viewport behavior in tiling WMs on X11 via the ImGui_ImplGlfw_SetWindowFloating() function. Note: using GLFW backend on Linux/BSD etc. requires linking with -lX11. (#8884, #8474, #8289)
 //  2025-07-08: Made ImGui_ImplGlfw_GetContentScaleForWindow(), ImGui_ImplGlfw_GetContentScaleForMonitor() helpers return 1.0f on Emscripten and Android platforms, matching macOS logic. (#8742, #8733)
@@ -816,7 +817,9 @@ void ImGui_ImplGlfw_Shutdown()
 {
     ImGui_ImplGlfw_Data* bd = ImGui_ImplGlfw_GetBackendData();
     IM_ASSERT(bd != nullptr && "No platform backend to shutdown, or already shutdown?");
+
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplGlfw_ShutdownMultiViewportSupport();
 
@@ -841,6 +844,7 @@ void ImGui_ImplGlfw_Shutdown()
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
+    platform_io.ClearPlatformHandlers();
     ImGui_ImplGlfw_ContextMap_Remove(bd->Window);
     IM_DELETE(bd);
 }

backends/imgui_impl_metal.mm

@@ -18,6 +18,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Metal: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplMetal_CreateFontsTexture() and ImGui_ImplMetal_DestroyFontsTexture().
 //  2025-02-03: Metal: Crash fix. (#8367)
 //  2025-01-08: Metal: Fixed memory leaks when using metal-cpp (#8276, #8166) or when using multiple contexts (#7419).
@@ -159,14 +160,17 @@ void ImGui_ImplMetal_Shutdown()
     ImGui_ImplMetal_Data* bd = ImGui_ImplMetal_GetBackendData();
     IM_UNUSED(bd);
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
+    ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+
     ImGui_ImplMetal_ShutdownMultiViewportSupport();
     ImGui_ImplMetal_DestroyDeviceObjects();
     ImGui_ImplMetal_DestroyBackendData();
 
-    ImGuiIO& io = ImGui::GetIO();
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
 }
 
 void ImGui_ImplMetal_NewFrame(MTLRenderPassDescriptor* renderPassDescriptor)

backends/imgui_impl_opengl2.cpp

@@ -27,6 +27,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-07-15: OpenGL: Set GL_UNPACK_ALIGNMENT to 1 before updating textures. (#8802)
 //  2025-06-11: OpenGL: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplOpenGL2_CreateFontsTexture() and ImGui_ImplOpenGL2_DestroyFontsTexture().
 //  2024-10-07: OpenGL: Changed default texture sampler to Clamp instead of Repeat/Wrap.
@@ -124,12 +125,15 @@ void    ImGui_ImplOpenGL2_Shutdown()
     ImGui_ImplOpenGL2_Data* bd = ImGui_ImplOpenGL2_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplOpenGL2_ShutdownMultiViewportSupport();
     ImGui_ImplOpenGL2_DestroyDeviceObjects();
+
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_opengl3.cpp

@@ -25,6 +25,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-07-22: OpenGL: Add and call embedded loader shutdown during ImGui_ImplOpenGL3_Shutdown() to facilitate multiple init/shutdown cycles in same process. (#8792)
 //  2025-07-15: OpenGL: Set GL_UNPACK_ALIGNMENT to 1 before updating textures (#8802) + restore non-WebGL/ES update path that doesn't require a CPU-side copy.
 //  2025-06-11: OpenGL: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplOpenGL3_CreateFontsTexture() and ImGui_ImplOpenGL3_DestroyFontsTexture().
@@ -430,12 +431,15 @@ void    ImGui_ImplOpenGL3_Shutdown()
     ImGui_ImplOpenGL3_Data* bd = ImGui_ImplOpenGL3_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplOpenGL3_ShutdownMultiViewportSupport();
     ImGui_ImplOpenGL3_DestroyDeviceObjects();
+
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 
 #ifdef IMGUI_IMPL_OPENGL_LOADER_IMGL3W

backends/imgui_impl_osx.mm

@@ -34,6 +34,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-07-08: [Docking] Fixed multi-viewport handling broken on 2025-06-02. (#8644, #8777)
 //  2025-06-27: Added ImGuiMouseCursor_Wait and ImGuiMouseCursor_Progress mouse cursor support.
 //  2025-06-12: ImGui_ImplOSX_HandleEvent() only process event for window containing our view. (#8644)
@@ -550,9 +551,12 @@ void ImGui_ImplOSX_Shutdown()
     ImGui_ImplOSX_ShutdownMultiViewportSupport();
     ImGui_ImplOSX_DestroyBackendData();
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
+
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports);
+    platform_io.ClearPlatformHandlers();
 }
 
 static void ImGui_ImplOSX_UpdateMouseCursor()

backends/imgui_impl_sdl2.cpp

@@ -26,6 +26,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-09-15: Content Scales are always reported as 1.0 on Wayland. (#8921)
 //  2025-07-08: Made ImGui_ImplSDL2_GetContentScaleForWindow(), ImGui_ImplSDL2_GetContentScaleForDisplay() helpers return 1.0f on Emscripten and Android platforms, matching macOS logic. (#8742, #8733)
 //  2025-06-11: Added ImGui_ImplSDL2_GetContentScaleForWindow(SDL_Window* window) and ImGui_ImplSDL2_GetContentScaleForDisplay(int display_index) helper to facilitate making DPI-aware apps.
@@ -702,6 +703,7 @@ void ImGui_ImplSDL2_Shutdown()
     ImGui_ImplSDL2_Data* bd = ImGui_ImplSDL2_GetBackendData();
     IM_ASSERT(bd != nullptr && "No platform backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplSDL2_ShutdownMultiViewportSupport();
 
@@ -714,6 +716,7 @@ void ImGui_ImplSDL2_Shutdown()
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
+    platform_io.ClearPlatformHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_sdl3.cpp

@@ -24,6 +24,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-09-15: Use SDL_GetWindowDisplayScale() on Mac to output DisplayFrameBufferScale. The function is more reliable during resolution changes e.g. going fullscreen. (#8703, #4414)
 //  2025-06-27: IME: avoid calling SDL_StartTextInput() again if already active. (#8727)
 //  2025-05-15: [Docking] Add Platform_GetWindowFramebufferScale() handler, to allow varying Retina display density on multiple monitors.
@@ -662,6 +663,7 @@ void ImGui_ImplSDL3_Shutdown()
     ImGui_ImplSDL3_Data* bd = ImGui_ImplSDL3_GetBackendData();
     IM_ASSERT(bd != nullptr && "No platform backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplSDL3_ShutdownMultiViewportSupport();
 
@@ -674,6 +676,7 @@ void ImGui_ImplSDL3_Shutdown()
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
+    platform_io.ClearPlatformHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_sdlgpu3.cpp

@@ -24,6 +24,7 @@
 
 // CHANGELOG
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-08-20: Added ImGui_ImplSDLGPU3_InitInfo::SwapchainComposition and ImGui_ImplSDLGPU3_InitInfo::PresentMode to configure how secondary viewports are created.
 //  2025-08-08: *BREAKING* Changed ImTextureID type from SDL_GPUTextureSamplerBinding* to SDL_GPUTexture*, which is more natural and easier for user to manage. If you need to change the current sampler, you can access the ImGui_ImplSDLGPU3_RenderState struct. (#8866, #8163, #7998, #7988)
 //  2025-08-08: Expose SamplerDefault and SamplerCurrent in ImGui_ImplSDLGPU3_RenderState. Allow callback to change sampler.
@@ -649,12 +650,15 @@ void ImGui_ImplSDLGPU3_Shutdown()
     ImGui_ImplSDLGPU3_Data* bd = ImGui_ImplSDLGPU3_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplSDLGPU3_ShutdownMultiViewportSupport();
     ImGui_ImplSDLGPU3_DestroyDeviceObjects();
+
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_sdlrenderer2.cpp

@@ -26,6 +26,7 @@
 // - Introduction, links and more at the top of imgui.cpp
 
 // CHANGELOG
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplSDLRenderer2_CreateFontsTexture() and ImGui_ImplSDLRenderer2_DestroyFontsTexture().
 //  2025-01-18: Use endian-dependent RGBA32 texture format, to match SDL_Color.
 //  2024-10-09: Expose selected render state in ImGui_ImplSDLRenderer2_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
@@ -96,12 +97,14 @@ void ImGui_ImplSDLRenderer2_Shutdown()
     ImGui_ImplSDLRenderer2_Data* bd = ImGui_ImplSDLRenderer2_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplSDLRenderer2_DestroyDeviceObjects();
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_sdlrenderer3.cpp

@@ -26,6 +26,7 @@
 // - Introduction, links and more at the top of imgui.cpp
 
 // CHANGELOG
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-11: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. Removed ImGui_ImplSDLRenderer3_CreateFontsTexture() and ImGui_ImplSDLRenderer3_DestroyFontsTexture().
 //  2025-01-18: Use endian-dependent RGBA32 texture format, to match SDL_Color.
 //  2024-10-09: Expose selected render state in ImGui_ImplSDLRenderer3_RenderState, which you can access in 'void* platform_io.Renderer_RenderState' during draw callbacks.
@@ -94,12 +95,14 @@ void ImGui_ImplSDLRenderer3_Shutdown()
     ImGui_ImplSDLRenderer3_Data* bd = ImGui_ImplSDLRenderer3_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplSDLRenderer3_DestroyDeviceObjects();
 
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_vulkan.cpp

@@ -29,6 +29,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-09-04: Vulkan: Added ImGui_ImplVulkan_CreateMainPipeline(). (#8110, #8111)
 //  2025-07-27: Vulkan: Fixed texture update corruption introduced on 2025-06-11. (#8801, #8755, #8840)
 //  2025-07-07: Vulkan: Fixed texture synchronization issue introduced on 2025-06-11. (#8772)
@@ -1352,6 +1353,7 @@ void ImGui_ImplVulkan_Shutdown()
     ImGui_ImplVulkan_Data* bd = ImGui_ImplVulkan_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     // First destroy objects in all viewports
     ImGui_ImplVulkan_DestroyDeviceObjects();
@@ -1368,6 +1370,7 @@ void ImGui_ImplVulkan_Shutdown()
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures | ImGuiBackendFlags_RendererHasViewports);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_wgpu.cpp

@@ -20,6 +20,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2025-09-18: Call platform_io.ClearRendererHandlers() on shutdown.
 //  2025-06-12: Added support for ImGuiBackendFlags_RendererHasTextures, for dynamic font atlas. (#8465)
 //  2025-02-26: Recreate image bind groups during render. (#8426, #8046, #7765, #8027) + Update for latest webgpu-native changes.
 //  2024-10-14: Update Dawn support for change of string usages. (#8082, #8083)
@@ -882,6 +883,7 @@ void ImGui_ImplWGPU_Shutdown()
     ImGui_ImplWGPU_Data* bd = ImGui_ImplWGPU_GetBackendData();
     IM_ASSERT(bd != nullptr && "No renderer backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ImGui_ImplWGPU_InvalidateDeviceObjects();
     delete[] bd->pFrameResources;
@@ -894,6 +896,7 @@ void ImGui_ImplWGPU_Shutdown()
     io.BackendRendererName = nullptr;
     io.BackendRendererUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_RendererHasVtxOffset | ImGuiBackendFlags_RendererHasTextures);
+    platform_io.ClearRendererHandlers();
     IM_DELETE(bd);
 }
 

backends/imgui_impl_win32.cpp

@@ -23,6 +23,7 @@
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
 //  2025-XX-XX: Platform: Added support for multiple windows via the ImGuiPlatformIO interface.
+//  2025-09-18: Call platform_io.ClearPlatformHandlers() on shutdown.
 //  2025-06-02: [Docking] WM_DPICHANGED also apply io.ConfigDpiScaleViewports for main viewport instead of letting it be done by application code.
 //  2025-04-30: Inputs: Fixed an issue where externally losing mouse capture (due to e.g. focus loss) would fail to claim it again the next subsequent click. (#8594)
 //  2025-03-26: [Docking] Viewports: fixed an issue when closing a window from the OS close button (with io.ConfigViewportsNoDecoration = false) while user code was discarding the 'bool* p_open = false' output from Begin(). Because we allowed the Win32 window to close early, Windows destroyed it and our imgui window became not visible even though user code was still submitting it.
@@ -245,6 +246,7 @@ void    ImGui_ImplWin32_Shutdown()
     ImGui_ImplWin32_Data* bd = ImGui_ImplWin32_GetBackendData();
     IM_ASSERT(bd != nullptr && "No platform backend to shutdown, or already shutdown?");
     ImGuiIO& io = ImGui::GetIO();
+    ImGuiPlatformIO& platform_io = ImGui::GetPlatformIO();
 
     ::SetPropA(bd->hWnd, "IMGUI_CONTEXT", nullptr);
     ImGui_ImplWin32_ShutdownMultiViewportSupport();
@@ -258,6 +260,7 @@ void    ImGui_ImplWin32_Shutdown()
     io.BackendPlatformName = nullptr;
     io.BackendPlatformUserData = nullptr;
     io.BackendFlags &= ~(ImGuiBackendFlags_HasMouseCursors | ImGuiBackendFlags_HasSetMousePos | ImGuiBackendFlags_HasGamepad | ImGuiBackendFlags_PlatformHasViewports | ImGuiBackendFlags_HasMouseHoveredViewport);
+    platform_io.ClearPlatformHandlers();
     IM_DELETE(bd);
 }
 

docs/CHANGELOG.txt

@@ -43,6 +43,12 @@ Breaking Changes:
 
 Other Changes:
 
+- IO: added ImGuiPlatformIO::ClearPlatformHandlers(), ClearRendererHandlers()
+  helpers to null all handlers. (#8945, #2769)
+- Backends: all backends call ImGuiPlatformIO::ClearPlatformHandlers() and
+  ClearRendererHandlers() on shutdown, so as not to leave function pointers
+  which may be dangling when using backend in e.g. DLL. (#8945, #2769)
+
 Docking+Viewports Branch:
 
 - Nav: fixed a crash that could occur when opening a popup following the processing

imgui.cpp

@@ -16224,6 +16224,23 @@ void ImGui::LocalizeRegisterEntries(const ImGuiLocEntry* entries, int count)
 // - DestroyPlatformWindows()
 //-----------------------------------------------------------------------------
 
+void ImGuiPlatformIO::ClearPlatformHandlers()
+{
+    Platform_GetClipboardTextFn = NULL;
+    Platform_SetClipboardTextFn = NULL;
+    Platform_ClipboardUserData = NULL;
+    Platform_OpenInShellFn = NULL;
+    Platform_OpenInShellUserData = NULL;
+    Platform_SetImeDataFn = NULL;
+    Platform_ImeUserData = NULL;
+}
+
+void ImGuiPlatformIO::ClearRendererHandlers()
+{
+    Renderer_TextureMaxWidth = Renderer_TextureMaxHeight = 0;
+    Renderer_RenderState = NULL;
+}
+
 ImGuiViewport* ImGui::GetMainViewport()
 {
     ImGuiContext& g = *GImGui;

imgui.h

@@ -4219,6 +4219,13 @@ struct ImGuiPlatformIO
     // Viewports list (the list is updated by calling ImGui::EndFrame or ImGui::Render)
     // (in the future we will attempt to organize this feature to remove the need for a "main viewport")
     ImVector<ImGuiViewport*>        Viewports;          // Main viewports, followed by all secondary viewports.
+
+    //------------------------------------------------------------------
+    // Functions
+    //------------------------------------------------------------------
+
+    void    ClearPlatformHandlers();    // Clear all Platform_XXX fields. Typically called on Platform Backend shutdown.
+    void    ClearRendererHandlers();    // Clear all Renderer_XXX fields. Typically called on Renderer Backend shutdown.
 };
 
 // (Optional) This is required when enabling multi-viewport. Represent the bounds of each connected monitor/display and their DPI.