re: bug#563. checking in some commented out trace code and a fix so that the in testalpha.c the background only flashes when alpha == 255. The problem that is being
fixed is caused by clearing SDL_COPY_RLE_COLORKEY without setting SDL_COPY_RLE_DESIRED in SDL_UnRELSurface.

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extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%402746