Do not text or take a screenshot. Though turning off your mobile has been mentioned, some people do need to stay connected, and setting the phone to silent or vibe is a good option if you must remain available (if you have a relative in the hospital, or own a business, etc.). Taking a quick look at a text message is distracting to others around you, but responding to it is rude. The light is very bright to those around you, so go out to the lobby or hall to reply. And taking screenshots should be right out anyhow - this is a copyright violation.