pub(crate) fn answer_frame_callbacks(state: &mut AppState)Expand description
Answer the frame callbacks of each captured display’s clients once a window, on its boundary:
the vblank a display gives them. A change renders as it lands (serve_changes), and a
client drawing on frame callbacks takes its clock from them, which the boundaries keep even.
The frame timer wakes at every boundary while a display captures, and calls this each time.