The flags parameter has been removed from SDL_CreateRenderer() and SDL_RENDERER_PRESENTVSYNC has been replaced with SDL_PROP_RENDERER_CREATE_PRESENT_VSYNC_NUMBER during window creation and SDL_PROP_RENDERER_VSYNC_NUMBER after renderer creation.
SDL_SetRenderVSync() now takes additional values besides 0 and 1.
The maximum texture size has been removed from SDL_RendererInfo, replaced with SDL_PROP_RENDERER_MAX_TEXTURE_SIZE_NUMBER.
Allow for the creation of SDL windows with a roleless surface that applications can use for their own purposes, such as with a windowing protocol other than XDG toplevel.
The property `wayland.surface_role_custom` will create a window with a surface that SDL can render to and handles input for, but is not associated with a toplevel window, so applications can use it for their own, custom purposes (e.g. wlr_layer_shell).
A test/minimal example is included in tests/testwaylandcustom.c
