Prevent SDL from using version 4 of the bitmap header when saving BMPs.
Defined in SDL_hints.h
#define SDL_HINT_BMP_SAVE_LEGACY_FORMAT "SDL_BMP_SAVE_LEGACY_FORMAT"
The bitmap header version 4 is required for proper alpha channel support and SDL will use it when required. Should this not be desired, this hint can force the use of the 40 byte header version which is supported everywhere.
The variable can be set to the following values:
The default value is "0".