Trick to take screenshots without notifying the sender:
Step 1: When you receive new message in the inbox, put your phone in flight mode without closing the app.
Step 2: Your device is disconnected still app will allow you to open the messages.
Steps 3: Take screen shots.
Step 4: Close the app completely and disable the flight mode.
http://www.news.com.au/technology/gadge ... ba739984ba