The render viewport is automatically re-centered when the window changes size, so applications that don't care will not have to handle recalculating their rendering coordinates.
Fixed API for drawing and filling multiple rectangles - the parameter should be an array of rects, not an array of pointers to rects.
Fixed API for updating window rects for consistency with other APIs - the order is pointer to array followed by count in array.
Fixed creating render texture framebuffer.
Removed the need for palette watch, added surface format caching.
Added an SDL_DONTFREE flag so you can't free the window and 1.2 shadow surfaces.
There's a new event that's always sent when the window changes size, and that event is what the renderers listen for to determine if they need to rebind their context.
The software renderer has been re-routed to use the framebuffer interface, which makes it possible to have software rendering available even on simple ports.