made Game Center's welcome banner show by having SDL display its inner UIWindow once on SDL window initialization, rather than on every frame

src/video/uikit/SDL_uikitopengles.m

@@ -90,9 +90,6 @@ void UIKit_GL_SwapWindow(_THIS, SDL_Window * window)
         return;
     }
     [data->view swapBuffers];
-    /* since now we've got something to draw
-       make the window visible */
-    [data->uiwindow makeKeyAndVisible];
 
     /* we need to let the event cycle run, or the OS won't update the OpenGL view! */
     SDL_PumpEvents();

src/video/uikit/SDL_uikitwindow.m

@@ -200,6 +200,9 @@ UIKit_CreateWindow(_THIS, SDL_Window *window)
     if (external) {
         [uiwindow setScreen:data->uiscreen];
     }
+    
+    // Make sure the native window gets displayed.
+    [uiwindow makeKeyAndVisible];
 
     if (SetupWindowData(_this, window, uiwindow, SDL_TRUE) < 0) {
         [uiwindow release];