For our project, we want to open our electron app from tray with a keypress on "Scroll Lock" (js keycode 145) but this is no registered accelerator that we can use.
atom/common/keyboard_util.cc
int flags = 0;
  if (modifiers & blink::WebInputEvent::kShiftKey)
    flags |= ui::EF_SHIFT_DOWN;
  if (modifiers & blink::WebInputEvent::kControlKey)
    flags |= ui::EF_CONTROL_DOWN;
  if (modifiers & blink::WebInputEvent::kAltKey)
    flags |= ui::EF_ALT_DOWN;
  if (modifiers & blink::WebInputEvent::kMetaKey)
    flags |= ui::EF_COMMAND_DOWN;
  if (modifiers & blink::WebInputEvent::kCapsLockOn)
    flags |= ui::EF_CAPS_LOCK_ON;
  if (modifiers & blink::WebInputEvent::kNumLockOn)
    flags |= ui::EF_NUM_LOCK_ON;
  if (modifiers & blink::WebInputEvent::kScrollLockOn)
    flags |= ui::EF_SCROLL_LOCK_ON;
  if (modifiers & blink::WebInputEvent::kLeftButtonDown)
    flags |= ui::EF_LEFT_MOUSE_BUTTON;
  if (modifiers & blink::WebInputEvent::kMiddleButtonDown)
    flags |= ui::EF_MIDDLE_MOUSE_BUTTON;
  if (modifiers & blink::WebInputEvent::kRightButtonDown)
    flags |= ui::EF_RIGHT_MOUSE_BUTTON;
  if (modifiers & blink::WebInputEvent::kIsAutoRepeat)
    flags |= ui::EF_IS_REPEAT;
  return flags;
}
}