These events accidentally slipping in sometimes appears to be a bug (or
maybe new behavior) in 10.10, as previous versions of Mac OS X don't appear
to ever trigger this.
Thanks to Paulo Marques for pointing out the fix on the SDL mailing list!
Fixes Bugzilla #2842 (again).
Volumetric
The "Unknown touch device" message appears because the initial touch device setup loop uses SDL_GetTouch() as a guard for calling SDL_AddTouch(). SDL_GetTouch() will always report "Unknown touch device" since the device hasn't been added yet. The SDL_GetTouch() call is unnecessary since SDL_AddTouch() calls SDL_GetTouchIndex() to verify that the device hasn't been added yet, and SDL_GetTouchIndex() has the benefit of not reporting an error for a device it can't find.
The backing scale factor can change when the window moves between retina and non-retina displays.
The only other way to detect such a change is to compare the output of SDL_GL_GetDrawableSize or SDL_GetRendererOutputSize every frame, which is less than desirable, especially since the necessary app logic is likely already being executed when a window resize event is received.
An existing hint lets apps that don't need the timer resolution changed avoid
this, to save battery, etc, but this fixes several problems in timing, audio
callbacks not firing fast enough, etc.
Fixes Bugzilla #2944.
