I updated SDL, and suddenly my SDL frames stopped working.  They'd "initialize" full of gibberish, and I couldn't render anything to them.  After a bit of digging, I found a problem: the renderer initialization routine in my SDL frame code wasn't getting called anymore.

procedure TSdlFrame.Paint;
begin
   if SDL_SelectRenderer(FWindowID) = -1 then
      CreateRenderer;
   SDL_RenderPresent;
end;

function TSdlFrame.CreateRenderer: boolean;
const
   pf: tagPIXELFORMATDESCRIPTOR = (nSize: sizeof(pf); nVersion: 1;
       dwFlags: PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER;
       iPixelType: PFD_TYPE_RGBA; cColorBits: 24; cAlphaBits: 8;
       iLayerType: PFD_MAIN_PLANE);

   RENDERERS: array[TRendererType] of AnsiString = ('software', 'gdi', 'opengl', 'd3d');
var
  pFormat: integer;
begin
   if (SDL_SelectRenderer(FWindowID) = 0) then
   begin
      result := true;
      Exit;
   end;
   if FRendererType = rtOpenGL then
   begin
      pFormat := ChoosePixelFormat(canvas.Handle, @pf);
      if not SetPixelFormat(canvas.Handle, pFormat, @pf) then
         outputDebugString(PChar(SysErrorMessage(GetLastError)));
      if wglCreateContext(canvas.Handle) = 0 then
         outputDebugString(PChar(SysErrorMessage(GetLastError)));
   end;
   if (SDL_CreateRenderer(FWindowID, SDL_RendererIndex(RENDERERS[FRendererType]), [sdlrPresentFlip3, sdlrAccelerated]) = 0) then
   begin
      SDL_ShowWindow(FWindowID);
      assert(SDL_SetRenderDrawColor(0, 0, 0, 255) = 0);
      FFlags := SDL_GetWindowFlags(FWindowID);
      if assigned(FOnAvailable) then
         FOnAvailable(self);
   end
   else outputDebugString(pChar(format('SDL_CreateRenderer failed: %s', [sdl_GetError])));
   result := SDL_SelectRenderer(FWindowID) = 0;
end;

This is a critical issue.  The Paint method gets called when the control receives a WM_PAINT message from Windows.  I can't create the renderer before then, or it will fail and cause trouble.  And when I do create it, it needs to be created with certain parameters.  So imagine my surprise when I started debugging into the DLL and found that SDL_SelectRenderer was trying to be "helpful" by creating the renderer for me if it didn't already exist!  Now not only does my initialization code not get called, I end up with the wrong renderer and so things don't render as expected when I try to use the window.