SDL_ResizeEvent is a member of the SDL_Event union and is used when an event of type SDL_VIDEORESIZE is reported.
When SDL_RESIZABLE is passed as a flag to SDL_SetVideoMode the user is allowed to resize the applications window. When the window is resized an SDL_VIDEORESIZE is report, with the new window width and height values stored in w and h, respectively. When an SDL_VIDEORESIZE is recieved the window should be resized to the new dimensions using SDL_SetVideoMode.