so i guess its a rule that when your windowed, flip true
and flip false when youre not.
I don't like to see tearing so I'd say "always flip true", but flipping false when windowed is particularly bad news and to be avoided, yes.
if its faked i wonder why its happening because its not convenient.
I guess it's tied to the way that Windows updates the screen and the disparity in where the last virtual scanline is as far as your app is concerned, where it physically rests on (or even off!) screen depending on the vertical position of the window, and the actual position of the genuine last scanline according to the dimensions of the desktop. If your application is playing nice, flipping true and waiting until the entire desktop is redrawn before considering the next frame then all is well, but you can appreciate how messy things can quickly become if it refuses to wait. (Just think - a non cpu-bound application running in a small window can have supplied the graphical data for several frames in the time it takes the OS to update the larger desktop on which it sits just once. Are those frames lost, are they buffered or is the application suspended? I don't know, but clearly there are bound to be problems if your application does not cooperate.)