Bug#870641: screen stays off after light-locker locked it and no way to turn it back on

[Aaron Lu <aaron.lwe@gmail.com>]

buster, light-locker 1.8.0-3

how to reproduce:
1 under xfce, lock the screen;
2 the display turned off
3 when I need to use it, pressing keyboard or moving mouse will not turn
  the screen back on.

I have this problem on both my laptop(which has a single integrated
intel card and my desktop which has an integraed intel card and an
additional ati card).

Workarounds for me:
1 Blindly type my password and hit enter and the screen will be back on
  with unlocked desktop - not ideal but usable.
2 hit ctrl-alt-f1(actually, any of f1-f7) will turn the screen back on
  and then press ctrl-alt-f8 will show me the lock screen and I can type
  my password there and unlock.

Hopefully this little problem can be solved. Thanks.