Backends: Null: added imgui_impl_null platform/renderer backend.

docs/BACKENDS.md

@@ -100,6 +100,7 @@ List of Renderer Backends:
 List of high-level Frameworks Backends (combining Platform + Renderer):
 
     imgui_impl_allegro5.cpp
+    imgui_impl_null.cpp
 
 Emscripten is also supported!
 The SDL2+GL, SDL3+GL, GLFW+GL and GLFW+WebGPU examples are all ready to build and run with Emscripten.

docs/CHANGELOG.txt

@@ -121,6 +121,8 @@ Other Changes:
    - Metrics: fixed table and columns rect highlight from display when
      debug/metrics window is not in the same viewport as the table.
 - Backends:
+  - Null: added imgui_impl_null platform/renderer backend.
+    This is designed if you need to run e.g. context with no input or no ouput.
   - GLFW: fixed building on Linux platforms where Wayland headers
     are not available. (#9024, #8969, #8921, #8920) [@jagot]
   - GLFW: lower minimum requirement from GLFW 3.1 to GLFW 3.0. Though

docs/EXAMPLES.md

@@ -109,9 +109,11 @@ Note that GLUT/FreeGLUT is largely obsolete software, prefer using GLFW or SDL.
 
 [example_null/](https://github.com/ocornut/imgui/blob/master/examples/example_null/) <BR>
 Null example, compile and link imgui, create context, run headless with no inputs and no graphics output. <BR>
-= main.cpp <BR>
+= main.cpp + imgui_impl_null.cpp<BR>
 This is used to quickly test compilation of core imgui files in as many setups as possible.
 Because this application doesn't create a window nor a graphic context, there's no graphics output.
+Please note that imgui_impl_null itself is a rather empty backend. We provide it for consistency but
+it is similarly easy to create a skeleton application without the null backend.
 
 [example_sdl2_directx11/](https://github.com/ocornut/imgui/blob/master/examples/example_sdl2_directx11/) <BR>
 SDL2 + DirectX11 example, Windows only. <BR>