Merge branch 'master' into docking

# Conflicts:
#	backends/imgui_impl_dx10.cpp
#	backends/imgui_impl_dx11.cpp
#	backends/imgui_impl_dx12.cpp
#	backends/imgui_impl_dx9.cpp
#	backends/imgui_impl_opengl3.cpp
#	backends/imgui_impl_win32.cpp
#	docs/CHANGELOG.txt
#	examples/example_glfw_vulkan/main.cpp
#	examples/example_sdl_vulkan/main.cpp
#	imgui.cpp

examples/example_allegro5/main.cpp

@@ -122,7 +122,7 @@ int main(int, char**)
 
         // Rendering
         ImGui::Render();
-        al_clear_to_color(al_map_rgba_f(clear_color.x, clear_color.y, clear_color.z, clear_color.w));
+        al_clear_to_color(al_map_rgba_f(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w));
         ImGui_ImplAllegro5_RenderDrawData(ImGui::GetDrawData());
         al_flip_display();
     }