I think the whole point of a "front" framebuffer is that its only purpose is to be written to the screen. You're only ever writing to the back buffer, which is

I think the whole point of a "front" framebuffer is that its only purpose is to be written to the screen. You're only ever writing to the back buffer, which is then flipped, at which point you're writing to a new buffer and it's the next frame. [edit: If I'm wrong... ouch. But it's been a while.]