Keep the boogar hook off the bang switch. If you don't want the lights to come on, keep the finger off the light switch.
They work about the same way. Big flashes of light can come out of a gun when the switch is flipped.
If you really want a thumb safety on a Glock, a certified Glock Armorer can install one for about $150.00.
But I don't have one, I'd forget to take it off when I needed to turn the light on.
