IGS_EXT_SPRITE_VISIBLE
if ((curctl & IGS_EXT_SPRITE_VISIBLE) == 0
curctl | IGS_EXT_SPRITE_VISIBLE);
else if ((curctl & IGS_EXT_SPRITE_VISIBLE) != 0
curctl & ~IGS_EXT_SPRITE_VISIBLE);
curctl &= ~IGS_EXT_SPRITE_VISIBLE;