Flip the back and front buffers of the current screen. The invisible area is now visible and vice versa, which allowss to do a 'double-buffering' effect (flicker free graphical displays). A screen must have been opened with OpenScreen() or OpenWindowedScreen(). The way the buffer are flipped (with or without synchronization) is set by OpenScreen() or OpenWindowedScreen().
FlipBuffers() has to be called outside a StartDrawing() : ... : StopDrawing() program block.