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_emscripten_opengl3/main.cpp

@@ -168,7 +168,7 @@ static void main_loop(void* arg)
     ImGui::Render();
     SDL_GL_MakeCurrent(g_Window, g_GLContext);
     glViewport(0, 0, (int)io.DisplaySize.x, (int)io.DisplaySize.y);
-    glClearColor(clear_color.x, clear_color.y, clear_color.z, clear_color.w);
+    glClearColor(clear_color.x * clear_color.w, clear_color.y * clear_color.w, clear_color.z * clear_color.w, clear_color.w);
     glClear(GL_COLOR_BUFFER_BIT);
     ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
     SDL_GL_SwapWindow(g_Window);