Hmmm I think ScreenTransition types won't affect background frame changing.
What colour depth was your game in?
If it's 256 colour, try to make the frames share the same palette when importing, if they use independent palettes I think that flash is hard to avoid.
What colour depth was your game in?
If it's 256 colour, try to make the frames share the same palette when importing, if they use independent palettes I think that flash is hard to avoid.