* Added clearer names for RGB pixel formats, e.g. SDL_PIXELFORMAT_XRGB8888, SDL_PIXELFORMAT_XBGR8888, etc.
Windows:
* Added the RAWINPUT controller driver to support more than 4 Xbox controllers simultaneously
* Added the hint SDL_HINT_JOYSTICK_RAWINPUT to control whether the RAWINPUT driver should be used
* Added the hint SDL_HINT_JOYSTICK_HIDAPI_CORRELATE_XINPUT to control whether XInput and WGI should be used to for complete controller functionality with the RAWINPUT driver.
macOS:
* Added the SDL_WINDOW_METAL flag to specify that a window should be created with a Metal view
* Added SDL_Metal_GetLayer() to get the CAMetalLayer backing a Metal view
* Added SDL_Metal_GetDrawableSize() to get the size of a window's drawable, in pixels
Linux:
* Added the hint SDL_HINT_AUDIO_DEVICE_APP_NAME to specify the name that shows up in PulseAudio for your application
* Added the hint SDL_HINT_AUDIO_DEVICE_STREAM_NAME to specify the name that shows up in PulseAudio associated with your audio stream
* Added the hint SDL_HINT_LINUX_JOYSTICK_DEADZONES to control whether HID defined dead zones should be respected on Linux
* Added the hint SDL_HINT_THREAD_PRIORITY_POLICY to specify the thread scheduler policy
* Added the hint SDL_HINT_THREAD_FORCE_REALTIME_TIME_CRITICAL to allow time critical threads to use a realtime scheduling policy
Android:
* Added SDL_AndroidRequestPermission() to request a specific system permission
* Added the hint SDL_HINT_ANDROID_BLOCK_ON_PAUSE_PAUSEAUDIO to control whether audio will pause when the application goes intot he background
OS/2:
* Added support for OS/2, see docs/README-os2.md for details
Emscripten (running in a web browser):
* Added the hint SDL_HINT_EMSCRIPTEN_ASYNCIFY to control whether SDL should call emscripten_sleep internally