关于PhoneWindowManager处理keycode return 值问题

/**
     * Called from the input dispatcher thread before a key is dispatched to a window.
     *
     * <p>Allows you to define
     * behavior for keys that can not be overridden by applications.
     * This method is called from the input thread, with no locks held.
     *
     * @param win The window that currently has focus.  This is where the key
     *            event will normally go.
     * @param event The key event.
     * @param policyFlags The policy flags associated with the key.
     * @return 0 if the key should be dispatched immediately, -1 if the key should
     * not be dispatched ever, or a positive value indicating the number of
     * milliseconds by which the key dispatch should be delayed before trying
     * again.
     */
    public long interceptKeyBeforeDispatching(WindowState win, KeyEvent event, int policyFlags);