In addition to lots of bug fixes, here are the major changes in this release:

General:

• Added SDL_RenderGetWindow() to get the window associated with a renderer
• Added floating point rectangle functions:
  • SDL_PointInFRect()
  • SDL_FRectEmpty()
  • SDL_FRectEquals()
  • SDL_FRectEqualsEpsilon()
  • SDL_HasIntersectionF()
  • SDL_IntersectFRect()
  • SDL_UnionFRect()
  • SDL_EncloseFPoints()
  • SDL_IntersectFRectAndLine()
• Added SDL_IsTextInputShown() which returns whether the IME window is currently shown
• Added SDL_ClearComposition() to dismiss the composition window without disabling IME input
• Added SDL_TEXTEDITING_EXT event for handling long composition text, and a hint SDL_HINT_IME_SUPPORT_EXTENDED_TEXT to enable it
• Added the hint SDL_HINT_MOUSE_RELATIVE_MODE_CENTER to control whether the mouse should be constrained to the whole window or the center of the window when relative mode is enabled
• The mouse is now automatically captured when mouse buttons are pressed, and the hint SDL_HINT_MOUSE_AUTO_CAPTURE allows you to control this behavior
• Added the hint SDL_HINT_VIDEO_FOREIGN_WINDOW_OPENGL to let SDL know that a foreign window will be used with OpenGL
• Added the hint SDL_HINT_VIDEO_FOREIGN_WINDOW_VULKAN to let SDL know that a foreign window will be used with Vulkan
• Added the hint SDL_HINT_QUIT_ON_LAST_WINDOW_CLOSE to specify whether an SDL_QUIT event will be delivered when the last application window is closed
• Added the hint SDL_HINT_JOYSTICK_ROG_CHAKRAM to control whether ROG Chakram mice show up as joysticks

Windows:

• Added support for SDL_BLENDOPERATION_MINIMUM and SDL_BLENDOPERATION_MAXIMUM to the D3D9 renderer

Linux:

• Compiling with Wayland support requires libwayland-client version 1.18.0 or later
• Added the hint SDL_HINT_X11_WINDOW_TYPE to specify the _NET_WM_WINDOW_TYPE of SDL windows
• Added the hint SDL_HINT_VIDEO_WAYLAND_PREFER_LIBDECOR to allow using libdecor with compositors that support xdg-decoration

Android:

• Added SDL_AndroidSendMessage() to send a custom command to the SDL java activity