anchor.diff:     *  The context must have been created with a compatible window.
      *}
   
  -  function SDL_GL_MakeCurrent(window: PSDLWindow; context: TSDLGLContext): SInt32;
  +  function SDL_GL_MakeCurrent(window: PSDLWindow; context: TSDLGLContext): SInt32 cdecl external {$IFDEF GPC} name 'SDL_GL_MakeCurrent' {$ELSE} SDL_LibName {$ENDIF};
   
     {**
      *  Set the swap interval for the current OpenGL context.
  
positive.code:    *  SDL_GL_SetSwapInterval()
     *}
  
    function SDL_GL_GetSwapInterval: SInt32;
  
    {**
     *  Swap the OpenGL buffers for a window, if double-buffering is
     *  supported.
     *}
  
    procedure SDL_GL_SwapWindow(SDL_Window * window);
  
    {**
     *  Delete an OpenGL context.
  
negative.code:    *  SDL_GL_UnloadLibrary()
     *}
  
    function SDL_GL_LoadLibrary(const path: PChar): SInt32 cdecl external {$IFDEF GPC} name 'SDL_GL_LoadLibrary' {$ELSE} SDL_LibName {$ENDIF};
  
    {**
     *  Get the address of an OpenGL function.
     *}
  
    function SDL_GL_GetProcAddress(const proc: PChar): Pointer cdecl external {$IFDEF GPC} name 'SDL_GL_GetProcAddress' {$ELSE} SDL_LibName {$ENDIF};
  
    {**
     *  Unload the OpenGL library previously loaded by SDL_GL_LoadLibrary().
     *  
     *  SDL_GL_LoadLibrary()
     *}
  
    procedure SDL_GL_UnloadLibrary cdecl external {$IFDEF GPC} name 'SDL_GL_UnloadLibrary' {$ELSE} SDL_LibName {$ENDIF};
  
    {**
     *  Return true if an OpenGL extension is supported for the current
     *  context.
     *}
  
    function SDL_GL_ExtensionSupported(const extension: PChar): TSDLBool cdecl external {$IFDEF GPC} name 'SDL_GL_ExtensionSupported' {$ELSE} SDL_LibName {$ENDIF};
  
    {**
     *  Set an OpenGL window attribute before window creation.
     *}
  
    function SDL_GL_SetAttribute(SDL_GLattr attr, int value): SInt32 cdecl external {$IFDEF GPC} name 'SDL_GL_SetAttribute' {$ELSE} SDL_LibName {$ENDIF};
  
    {**
     *  Get the actual value for an attribute from the current context.
     *}
  
    function SDL_GL_GetAttribute(SDL_GLattr attr, int *value): SInt32 cdecl external {$IFDEF GPC} name 'SDL_GL_GetAttribute' {$ELSE} SDL_LibName {$ENDIF};
  
    {**
     *  Create an OpenGL context for use with an OpenGL window, and make it
  