[SDL] SDL_BlitSurface on MacOSX 10.3.9

[Michael Ryan Bannon]

Hello,

I'm using SDL_BlitSurface to blend two 800x600 backgrounds.  One background 
stays at an alpha at 255 and goes to 0 while the other one, on top of it, 
goes from 0 to 255 at the same rate.  Everything works fine except for one 
odd anomoly: my code works fine on MacOSX 10.4.6 version but not on my 
10.3.9.  On the 10.3.9 machine, the back image (the one starting at 255) is 
shifted to the right about 5 pixels.  I even tried to simplfy it by doing 
the following:

SDL_BlitSurface(srcSurface, NULL, targetSurface, NULL);

I can remedy the problem by setting the position of the backgrounds to the 
right one pixel.

SDL_Rect rect;
rect.x = 1;
rect.y = 0;
...
SDL_BlitSurface(srcSurface, NULL, m_targetSurface, rect);

This works on both OSs, however I would then have a small black line on the 
left side of my window.
Has anybody seen this problem before or have any idea what might be causing 
it?  I can provide more info if needed.

Thanks,

Ryan